Variable Interest Entities (Schedule of Aggregate Assets, Liabilities, and Our Exposure to Loss from those VIEs) (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Variable Interest Entity [Line Items]
Assets	$ 37,809,278	$ 37,727,460
Total liabilities	32,411,071	32,433,029
Variable Interest Entity Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets	288,162
Variable Interest Entity Not Primary Beneficiary [Member] | Debt and equity [member]
Variable Interest Entity [Line Items]
Assets	676,928	798,266
Total liabilities	190,776	278,602
Maximum Exposure to Loss	38,296	40,088
Variable Interest Entity Not Primary Beneficiary [Member] | Miscellaneous Investments [Member]
Variable Interest Entity [Line Items]
Assets	388,766	456,286
Total liabilities	189,831	277,924
Maximum Exposure to Loss	38,296	40,088
Variable Interest Entity Not Primary Beneficiary [Member] | Partnership Interest [Member]
Variable Interest Entity [Line Items]
Assets		341,980
Total liabilities	945	678
Maximum Exposure to Loss	$ 0	$ 0