Derivative Instruments (Offsetting Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Offsetting of Financial Assets, Derivatives
Gross Amounts of Recognized Financial Instruments	$ 1,477,909	$ 14,819,236
Gross Amounts Offset in the Statements of Financial Position	(1,474,780)	(14,624,985)
Net Amounts Presented in the Statements of Financial Position	3,129	194,251
Financial Instruments/Collateral	0	0
Net Amount	3,129	194,251
Securities purchased under agreement to resell
Gross Amounts of Recognized Financial Instruments	0	150,000
Gross Amounts Offset in the Statements of Financial Position	0	0
Net Amounts Presented in the Statements of Financial Position	0	150,000
Financial Instruments/Collateral	0	(150,000)
Net Amount	0	0
Total Assets
Gross Amounts of Recognized Financial Instruments	1,477,909	14,969,236
Gross Amounts Offset in the Statements of Financial Position	(1,474,780)	(14,624,985)
Net Amounts Presented in the Statements of Financial Position	3,129	344,251
Financial Instruments/Collateral	0	(150,000)
Net Amount	3,129	194,251
Offsetting of Financial Liabilities, Derivatives
Gross Amounts of Recognized Financial Instruments	1,368,213	11,952,846
Gross Amounts Offset in the Statements of Financial Position	(1,153,610)	(11,936,059)
Net Amounts Presented in the Statements of Financial Position	214,603	16,787
Financial Instruments/Collateral	(214,603)	(16,787)
Net Amount	0	0
Securities sold under agreement to repurchase
Gross Amounts of Recognized Financial Instruments	0	0
Gross Amounts Offset in the Statements of Financial Position	0	0
Net Amounts Presented in the Statements of Financial Position	0	0
Financial Instruments/Collateral	0	0
Net Amount	0	0
Total Liabilities
Gross Amounts of Recognized Financial Instruments	1,368,213	11,952,846
Gross Amounts Offset in the Statements of Financial Position	(1,153,610)	(11,936,059)
Net Amounts Presented in the Statements of Financial Position	214,603	16,787
Financial Instruments/Collateral	(214,603)	(16,787)
Net Amount	$ 0	$ 0