Derivative Instruments and Hedging Activities U.S. Treasury and Eurodollar Futures (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Derivative [Line Items]
Notional	$ (18,878,215,000)	$ (17,159,801,000)	$ (19,137,094,000)	$ (23,932,603,000)
U.S. Treasury and Eurodollar Futures [Member]
Derivative [Line Items]
Fair Value	$ 0	$ 35,362,000
Weighted Average Remaining Maturity	327 days	370 days
U.S. Treasury and Eurodollar Futures [Member] | Net Short Position [Member]
Derivative [Line Items]
Notional	$ (7,516,650,000)	$ (5,829,600,000)		$ (2,021,100,000)
U.S. Treasury and Eurodollar Futures [Member] | Net Long Position [Member]
Derivative [Line Items]
Notional			$ (1,185,100,000)
U.S. Treasury and Eurodollar Futures [Member] | U.S. Treasury Futures [Member]
Derivative [Line Items]
Fair Value	$ 0	$ 1,809,000
Weighted Average Remaining Maturity	91 days	90 days
U.S. Treasury and Eurodollar Futures [Member] | U.S. Treasury Futures [Member] | Net Short Position [Member]
Derivative [Line Items]
Notional	$ (238,400,000)
U.S. Treasury and Eurodollar Futures [Member] | U.S. Treasury Futures [Member] | Net Long Position [Member]
Derivative [Line Items]
Notional		$ (687,900,000)
U.S. Treasury and Eurodollar Futures [Member] | Eurodollar Futures [Member] | Derivative Maturity Within One Year From Balance Sheet Date [Member]
Derivative [Line Items]
Fair Value	$ 0	$ 15,121,000
Weighted Average Remaining Maturity	232 days	213 days
U.S. Treasury and Eurodollar Futures [Member] | Eurodollar Futures [Member] | Derivative Maturity Within One Year From Balance Sheet Date [Member] | Net Short Position [Member]
Derivative [Line Items]
Notional	$ (4,707,000,000)	$ (3,582,000,000)
U.S. Treasury and Eurodollar Futures [Member] | Eurodollar Futures [Member] | Derivative Maturity Over One And Within Two Years From Balance Sheet Date [Member]
Derivative [Line Items]
Fair Value	$ 0	$ 14,952,000
Weighted Average Remaining Maturity	550 days	560 days
U.S. Treasury and Eurodollar Futures [Member] | Eurodollar Futures [Member] | Derivative Maturity Over One And Within Two Years From Balance Sheet Date [Member] | Net Short Position [Member]
Derivative [Line Items]
Notional	$ (2,238,250,000)	$ (2,269,500,000)
U.S. Treasury and Eurodollar Futures [Member] | Eurodollar Futures [Member] | Derivative Maturity Over Two And Within Three Years From Balance Sheet Date [Member]
Derivative [Line Items]
Fair Value	$ 0	$ 3,480,000
Weighted Average Remaining Maturity	809 days	854 days
U.S. Treasury and Eurodollar Futures [Member] | Eurodollar Futures [Member] | Derivative Maturity Over Two And Within Three Years From Balance Sheet Date [Member] | Net Short Position [Member]
Derivative [Line Items]
Notional	$ (333,000,000)	$ (666,000,000)