Derivative Instruments (Offsetting Assets and Liabilities) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Derivatives Assets
Gross Amounts of Recognized Financial Instruments	$ 12,024,588	$ 9,045,718
Gross Amounts Offset in the Consolidated Statement of Financial Position	(11,993,839)	(9,028,019)
Net Amounts Presented in the Consolidated Statement of Financial Position	30,749	17,699
Financial Instruments/Collateral	0	0
Net Amount	30,749	17,699
Securities Purchased under Agreements to Resell
Gross Amounts of Recognized Financial Instruments	0	25,000
Gross Amounts Offset in the Consolidated Statement of Financial Position	0	0
Net Amounts Presented in the Consolidated Statement of Financial Position	0	25,000
Financial Instruments/Collateral	0	0
Net Amount	0	25,000
Total Assets
Gross Amounts of Recognized Financial Instruments	12,024,588	9,070,718
Gross Amounts Offset in the Consolidated Statement of Financial Position	(11,993,839)	(9,028,019)
Net Amounts Presented in the Consolidated Statement of Financial Position	30,749	42,699
Financial Instruments/Collateral	0	0
Net Amount	30,749	42,699
Derivatives Liabilities
Gross Amounts of Recognized Financial Instruments	23,458,684	21,248,026
Gross Amounts Offset in the Consolidated Statement of Financial Position	(20,971,250)	(18,596,679)
Net Amounts Presented in the Consolidated Statement of Financial Position	2,487,434	2,651,347
Financial Instruments/Collateral	(2,487,434)	(2,651,347)
Net Amount	0	0
Securities Sold under Agreements to Repurchase
Gross Amounts of Recognized Financial Instruments	0	0
Gross Amounts Offset in the Consolidated Statement of Financial Position	0	0
Net Amounts Presented in the Consolidated Statement of Financial Position	0	0
Financial Instruments/Collateral	0	0
Net Amount	0	0
Total Liabilities
Gross Amounts of Recognized Financial Instruments	23,458,684	21,248,026
Gross Amounts Offset in the Consolidated Statement of Financial Position	(20,971,250)	(18,596,679)
Net Amounts Presented in the Consolidated Statement of Financial Position	2,487,434	2,651,347
Financial Instruments/Collateral	(2,487,434)	(2,651,347)
Net Amount	$ 0	$ 0