| | 2021-12-31 | 2022-12-31 | 2023-12-31 | 2024-12-31 | 2025-06-30 | 2025-12-31 |
| Amortization Of Securities | | 422400000.0 | 428100000.0 | 431000000.0 | | 480500000.0 |
| Beginning Cash Position | | 2332000000.0 | 4848000000.0 | 4707700000.0 | 4816600000.0 | 4211900000.0 |
| Capital Expenditure | | -116300000.0 | -102000000.0 | -68800000.0 | -73700000.0 | -98000000.0 |
| Cash Dividends Paid | | -642300000.0 | -625500000.0 | -658400000.0 | -669500000.0 | -684000000.0 |
| Cash Flow From Continuing Financing Activities | | -1715400000.0 | -2585800000.0 | 300300000.0 | -563400000.0 | -181800000.0 |
| Cash Flow From Continuing Investing Activities | | 1058500000.0 | -1346900000.0 | -5399000000.0 | -4970400000.0 | -4135800000.0 |
| Cash Flow From Continuing Operating Activities | | 3172900000.0 | 3792400000.0 | 4602900000.0 | | 4536700000.0 |
| Change In Other Working Capital | | 4234900000.0 | -490800000.0 | 74400000.0 | | 217100000.0 |
| Change In Receivables | | -3301900000.0 | -36700000.0 | 53100000.0 | | -181000000.0 |
| Change In Working Capital | | 2461900000.0 | 1934400000.0 | 2692400000.0 | | 2602100000.0 |
| Changes In Account Receivables | | -3301900000.0 | -36700000.0 | 53100000.0 | | -181000000.0 |
| Changes In Cash | | 2516000000.0 | -140300000.0 | -495800000.0 | -1157600000.0 | 219100000.0 |
| Common Stock Dividend Paid | | -642300000.0 | -625500000.0 | -658400000.0 | -669500000.0 | -684000000.0 |
| Common Stock Issuance | | 181700000.0 | 57800000.0 | 67700000.0 | 61100000.0 | 43700000.0 |
| Common Stock Payments | | -1695000000.0 | -740400000.0 | -1042400000.0 | -957500000.0 | -902700000.0 |
| Depreciation And Amortization | | 295900000.0 | 272700000.0 | 256200000.0 | | 251400000.0 |
| Earnings Losses From Equity Investments | | -111000000.0 | -110200000.0 | 10900000.0 | | -127700000.0 |
| End Cash Position | | 4848000000.0 | 4707700000.0 | 4211900000.0 | 3659000000.0 | 4431000000.0 |
| Financing Cash Flow | | -1715400000.0 | -2585800000.0 | 300300000.0 | -563400000.0 | -181800000.0 |
| Free Cash Flow | | 3056600000.0 | 3690400000.0 | 4534100000.0 | 4302500000.0 | 4438700000.0 |
| Gain Loss On Investment Securities | | 233100000.0 | 95700000.0 | 160700000.0 | | 69400000.0 |
| Gain Loss On Sale Of Business | | -749400000.0 | -165000000.0 | -87700000.0 | | -43200000.0 |
| Income Tax Paid Supplemental Data | | 142100000.0 | 68100000.0 | 117700000.0 | | 220700000.0 |
| Interest Paid Supplemental Data | | 175800000.0 | 170700000.0 | 170300000.0 | | 172600000.0 |
| Investing Cash Flow | | 1058500000.0 | -1346900000.0 | -5399000000.0 | -4970400000.0 | -4135800000.0 |
| Issuance Of Capital Stock | | 181700000.0 | 57800000.0 | 67700000.0 | 61100000.0 | 43700000.0 |
| Issuance Of Debt | | 15400000.0 | 691500000.0 | 21800000.0 | | 0.0 |
| Long Term Debt Issuance | | 15400000.0 | 691500000.0 | 21800000.0 | | 0.0 |
| Long Term Debt Payments | | -302000000.0 | -764000000.0 | -100000.0 | -400100000.0 | -400100000.0 |
| Net Business Purchase And Sale | | 0.0 | 0.0 | -27100000.0 | | -5600000.0 |
| Net Common Stock Issuance | | -1513300000.0 | -682600000.0 | -974700000.0 | -896400000.0 | -859000000.0 |
| Net Income From Continuing Operations | | 4797500000.0 | 670100000.0 | 1597900000.0 | | 1255500000.0 |
| Net Investment Properties Purchase And Sale | | 128800000.0 | -55500000.0 | -42000000.0 | -130300000.0 | 65500000.0 |
| Net Investment Purchase And Sale | | 2162600000.0 | -1257200000.0 | -4707300000.0 | -4147100000.0 | -3519000000.0 |
| Net Issuance Payments Of Debt | | -285700000.0 | -91000000.0 | 119600000.0 | -285300000.0 | -409100000.0 |
| Net Long Term Debt Issuance | | -286600000.0 | -72500000.0 | 21700000.0 | | -400100000.0 |
| Net Other Financing Charges | | 725900000.0 | -1186700000.0 | 1813800000.0 | 1287800000.0 | 1770300000.0 |
| Net PPEPurchase And Sale | | -116300000.0 | -102000000.0 | -68800000.0 | -73700000.0 | -98000000.0 |
| Net Short Term Debt Issuance | | 900000.0 | -18500000.0 | 97900000.0 | 93000000.0 | -9000000.0 |
| Operating Cash Flow | | 3172900000.0 | 3792400000.0 | 4602900000.0 | 4376200000.0 | 4536700000.0 |
| Operating Gains Losses | | -627300000.0 | -179500000.0 | 83900000.0 | | -101500000.0 |
| Other Non Cash Items | | -565000000.0 | -495000000.0 | 13600000.0 | | -345200000.0 |
| Purchase Of Business | | 0.0 | 0.0 | -27100000.0 | | -5600000.0 |
| Purchase Of Investment | | -19420800000.0 | -12336300000.0 | -15662100000.0 | -17182300000.0 | -16335400000.0 |
| Purchase Of Investment Properties | | -245200000.0 | -187500000.0 | -167800000.0 | -161600000.0 | -135500000.0 |
| Purchase Of PPE | | -116300000.0 | -102000000.0 | -68800000.0 | -73700000.0 | -98000000.0 |
| Repayment Of Debt | | -302000000.0 | -764000000.0 | -100000.0 | -405000000.0 | -400100000.0 |
| Repurchase Of Capital Stock | | -1695000000.0 | -740400000.0 | -1042400000.0 | -957500000.0 | -902700000.0 |
| Sale Of Business | 27000000.0 | 0.0 | 0.0 | | | |
| Sale Of Investment | | 21583400000.0 | 11079100000.0 | 10954800000.0 | 13035200000.0 | 12816400000.0 |
| Sale Of Investment Properties | | 374000000.0 | 132000000.0 | 125800000.0 | 31300000.0 | 201000000.0 |
| Short Term Debt Issuance | 10200000.0 | 900000.0 | | | | |
| Stock Based Compensation | | 91300000.0 | 99400000.0 | 108700000.0 | | 109900000.0 |
| Unrealized Gain Loss On Investment Securities | | 185300000.0 | -55400000.0 | -130000000.0 | | -120100000.0 |