Variable Interest Entities (Schedule of Aggregate Assets, Liabilities, and Our Exposure to Loss from those VIEs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Variable Interest Entity [Line Items]
Assets	$ 37,727,460	$ 37,196,124
Total liabilities	32,433,029	31,867,653
Variable Interest Entity Not Primary Beneficiary [Member] | Debt and Equity [Member]
Variable Interest Entity [Line Items]
Assets	798,266	791,111
Total liabilities	278,602	297,555
Gain (Loss) on Price Risk Derivatives, Net	40,088	14,776
Variable Interest Entity Not Primary Beneficiary [Member] | Miscellaneous Investments [Member]
Variable Interest Entity [Line Items]
Assets	456,286	388,408
Total liabilities	277,924	296,375
Gain (Loss) on Price Risk Derivatives, Net	40,088	14,776
Variable Interest Entity Not Primary Beneficiary [Member] | Partnership Interests [Member]
Variable Interest Entity [Line Items]
Assets	341,980	402,703
Total liabilities	678	1,180
Gain (Loss) on Price Risk Derivatives, Net	$ 0	$ 0