| | 2021-12-31 | 2022-12-31 | 2023-12-31 | 2024-12-31 | 2025-06-30 | 2025-09-30 |
| Amortization Of Securities | 405800000.0 | 422400000.0 | 428100000.0 | 431000000.0 | | |
| Beginning Cash Position | 2849800000.0 | 2332000000.0 | 4848000000.0 | 4707700000.0 | 4816600000.0 | 6174500000.0 |
| Capital Expenditure | -129900000.0 | -116300000.0 | -102000000.0 | -68800000.0 | -73700000.0 | -80500000.0 |
| Cash Dividends Paid | -654100000.0 | -642300000.0 | -625500000.0 | -658400000.0 | -669500000.0 | -677300000.0 |
| Cash Flow From Continuing Financing Activities | 1921500000.0 | -1715400000.0 | -2585800000.0 | 300300000.0 | -563400000.0 | -484400000.0 |
| Cash Flow From Continuing Investing Activities | -5693700000.0 | 1058500000.0 | -1346900000.0 | -5399000000.0 | -4970400000.0 | -4805000000.0 |
| Cash Flow From Continuing Operating Activities | 3254400000.0 | 3172900000.0 | 3792400000.0 | 4602900000.0 | | |
| Change In Other Working Capital | 90900000.0 | 4234900000.0 | -490800000.0 | 74400000.0 | | |
| Change In Receivables | 8300000.0 | -3301900000.0 | -36700000.0 | 53100000.0 | | |
| Change In Working Capital | 1643500000.0 | 2461900000.0 | 1934400000.0 | 2692400000.0 | | |
| Changes In Account Receivables | 8300000.0 | -3301900000.0 | -36700000.0 | 53100000.0 | | |
| Changes In Cash | -517800000.0 | 2516000000.0 | -140300000.0 | -495800000.0 | -1157600000.0 | -1037400000.0 |
| Common Stock Dividend Paid | -654100000.0 | -642300000.0 | -625500000.0 | -658400000.0 | -669500000.0 | -677300000.0 |
| Common Stock Issuance | 86700000.0 | 181700000.0 | 57800000.0 | 67700000.0 | 61100000.0 | 58200000.0 |
| Common Stock Payments | -937200000.0 | -1695000000.0 | -740400000.0 | -1042400000.0 | -957500000.0 | -933400000.0 |
| Depreciation And Amortization | 275300000.0 | 295900000.0 | 272700000.0 | 256200000.0 | | |
| Earnings Losses From Equity Investments | -189800000.0 | -111000000.0 | -110200000.0 | 10900000.0 | | |
| End Cash Position | 2332000000.0 | 4848000000.0 | 4707700000.0 | 4211900000.0 | 3659000000.0 | 5137100000.0 |
| Financing Cash Flow | 1921500000.0 | -1715400000.0 | -2585800000.0 | 300300000.0 | -563400000.0 | -484400000.0 |
| Free Cash Flow | 3124500000.0 | 3056600000.0 | 3690400000.0 | 4534100000.0 | 4302500000.0 | 4171500000.0 |
| Gain Loss On Investment Securities | -62200000.0 | 233100000.0 | 95700000.0 | 160700000.0 | | |
| Gain Loss On Sale Of Business | 0.0 | -749400000.0 | -165000000.0 | -87700000.0 | | |
| Income Tax Paid Supplemental Data | 109900000.0 | 142100000.0 | 68100000.0 | 117700000.0 | | |
| Interest Paid Supplemental Data | 166100000.0 | 175800000.0 | 170700000.0 | 170300000.0 | | |
| Investing Cash Flow | -5693700000.0 | 1058500000.0 | -1346900000.0 | -5399000000.0 | -4970400000.0 | -4805000000.0 |
| Issuance Of Capital Stock | 86700000.0 | 181700000.0 | 57800000.0 | 67700000.0 | 61100000.0 | 58200000.0 |
| Issuance Of Debt | 0.0 | 15400000.0 | 691500000.0 | 21800000.0 | | |
| Long Term Debt Issuance | 0.0 | 15400000.0 | 691500000.0 | 21800000.0 | | |
| Long Term Debt Payments | -1800000.0 | -302000000.0 | -764000000.0 | -100000.0 | -400100000.0 | -400100000.0 |
| Net Business Purchase And Sale | 27000000.0 | 0.0 | 0.0 | -27100000.0 | | 500000.0 |
| Net Common Stock Issuance | -850500000.0 | -1513300000.0 | -682600000.0 | -974700000.0 | -896400000.0 | -875200000.0 |
| Net Income From Continuing Operations | 1627000000.0 | 4797500000.0 | 670100000.0 | 1597900000.0 | | |
| Net Investment Properties Purchase And Sale | -147700000.0 | 128800000.0 | -55500000.0 | -42000000.0 | -130300000.0 | 16000000.0 |
| Net Investment Purchase And Sale | -3072800000.0 | 2162600000.0 | -1257200000.0 | -4707300000.0 | -4147100000.0 | -3892200000.0 |
| Net Issuance Payments Of Debt | 8400000.0 | -285700000.0 | -91000000.0 | 119600000.0 | -285300000.0 | -281200000.0 |
| Net Long Term Debt Issuance | -1800000.0 | -286600000.0 | -72500000.0 | 21700000.0 | | -378300000.0 |
| Net Other Financing Charges | 3417700000.0 | 725900000.0 | -1186700000.0 | 1813800000.0 | 1287800000.0 | 1349300000.0 |
| Net PPEPurchase And Sale | -129900000.0 | -116300000.0 | -102000000.0 | -68800000.0 | -73700000.0 | -80500000.0 |
| Net Short Term Debt Issuance | 10200000.0 | 900000.0 | -18500000.0 | 97900000.0 | 93000000.0 | 97100000.0 |
| Operating Cash Flow | 3254400000.0 | 3172900000.0 | 3792400000.0 | 4602900000.0 | 4376200000.0 | 4252000000.0 |
| Operating Gains Losses | -252000000.0 | -627300000.0 | -179500000.0 | 83900000.0 | | |
| Other Non Cash Items | -488100000.0 | -565000000.0 | -495000000.0 | 13600000.0 | | |
| Purchase Of Business | 0.0 | 0.0 | 0.0 | -27100000.0 | | 500000.0 |
| Purchase Of Investment | -16768100000.0 | -19420800000.0 | -12336300000.0 | -15662100000.0 | -17182300000.0 | -16966100000.0 |
| Purchase Of Investment Properties | -281400000.0 | -245200000.0 | -187500000.0 | -167800000.0 | -161600000.0 | -144900000.0 |
| Purchase Of PPE | -129900000.0 | -116300000.0 | -102000000.0 | -68800000.0 | -73700000.0 | -80500000.0 |
| Repayment Of Debt | -1800000.0 | -302000000.0 | -764000000.0 | -100000.0 | -405000000.0 | -400100000.0 |
| Repurchase Of Capital Stock | -937200000.0 | -1695000000.0 | -740400000.0 | -1042400000.0 | -957500000.0 | -933400000.0 |
| Sale Of Business | 27000000.0 | 0.0 | 0.0 | | | |
| Sale Of Investment | 13695300000.0 | 21583400000.0 | 11079100000.0 | 10954800000.0 | 13035200000.0 | 13073900000.0 |
| Sale Of Investment Properties | 133700000.0 | 374000000.0 | 132000000.0 | 125800000.0 | 31300000.0 | 160900000.0 |
| Short Term Debt Issuance | 10200000.0 | 900000.0 | | | | |
| Stock Based Compensation | 96100000.0 | 91300000.0 | 99400000.0 | 108700000.0 | | |
| Unrealized Gain Loss On Investment Securities | -66700000.0 | 185300000.0 | -55400000.0 | -130000000.0 | | |