Derivative Instruments (Offsetting Assets and Liabilities) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Derivatives Assets
Gross Amounts of Recognized Financial Instruments	$ 12,311,325	$ 7,685,050
Gross Amounts Offset in the Consolidated Statement of Financial Position	(12,276,734)	(7,637,939)
Net Amounts Presented in the Consolidated Statement of Financial Position	34,591	47,111
Financial Instruments/Collateral	0	0
Net Amount	34,591	47,111
Securities Purchased under Agreements to Resell
Gross Amounts of Recognized Financial Instruments	140,000	290,000
Gross Amounts Offset in the Consolidated Statement of Financial Position	0	0
Net Amounts Presented in the Consolidated Statement of Financial Position	140,000	290,000
Financial Instruments/Collateral	0	(290,000)
Net Amount	140,000	0
Total Assets
Gross Amounts of Recognized Financial Instruments	12,451,325	7,975,050
Gross Amounts Offset in the Consolidated Statement of Financial Position	(12,276,734)	(7,637,939)
Net Amounts Presented in the Consolidated Statement of Financial Position	174,591	337,111
Financial Instruments/Collateral	0	(290,000)
Net Amount	174,591	47,111
Derivatives Liabilities
Gross Amounts of Recognized Financial Instruments	25,816,497	18,654,072
Gross Amounts Offset in the Consolidated Statement of Financial Position	(21,871,933)	(16,568,912)
Net Amounts Presented in the Consolidated Statement of Financial Position	3,944,564	2,085,160
Financial Instruments/Collateral	(3,944,564)	(2,085,160)
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	25,816,497	18,654,072
Gross Amounts Offset in the Consolidated Statement of Financial Position	(21,871,933)	(16,568,912)
Net Amounts Presented in the Consolidated Statement of Financial Position	3,944,564	2,085,160
Financial Instruments/Collateral	(3,944,564)	(2,085,160)
Net Amount	$ 0	$ 0