Derivative Activities - Offsetting of Derivative Assets - Derivative Liabilities, Financial Liabilities, and Collateral Held by Counterparty (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Derivative liabilities:
Net amounts of liabilities presented in the consolidated balance sheet	$ 7,319,966	$ 9,706,633
Financial instruments	(7,297,360)	(9,663,995)
Net amount of liabilities in the consolidated balance sheet	22,606	42,638
Credit Suisse First Boston Mortgage Capital LLC
Derivative liabilities:
Net amounts of liabilities presented in the consolidated balance sheet	1,974,278	3,947,752
Financial instruments	(1,969,670)	(3,943,149)
Net amount of liabilities in the consolidated balance sheet	4,608	4,603
JP Morgan
Derivative liabilities:
Net amounts of liabilities presented in the consolidated balance sheet	300,912	2,752,279
Financial instruments	(300,912)	(2,752,279)
Bank of America, N.A.
Derivative liabilities:
Net amounts of liabilities presented in the consolidated balance sheet	1,758,690	634,523
Financial instruments	(1,758,690)	(626,550)
Net amount of liabilities in the consolidated balance sheet		7,973
Barclays
Derivative liabilities:
Net amounts of liabilities presented in the consolidated balance sheet	677,419	596,729
Financial instruments	(676,685)	(596,729)
Net amount of liabilities in the consolidated balance sheet	734
Citibank, N.A.
Derivative liabilities:
Net amounts of liabilities presented in the consolidated balance sheet	403,003	505,625
Financial instruments	(402,806)	(505,625)
Net amount of liabilities in the consolidated balance sheet	197
Royal Bank of Canada
Derivative liabilities:
Net amounts of liabilities presented in the consolidated balance sheet	496,064	406,348
Financial instruments	(496,064)	(406,348)
BNP Paribas
Derivative liabilities:
Net amounts of liabilities presented in the consolidated balance sheet	349,172	337,823
Financial instruments	(349,172)	(336,545)
Net amount of liabilities in the consolidated balance sheet		1,278
Morgan Stanley Bank, N.A.
Derivative liabilities:
Net amounts of liabilities presented in the consolidated balance sheet	299,580	331,546
Financial instruments	(292,105)	(331,546)
Net amount of liabilities in the consolidated balance sheet	7,475
Wells Fargo Bank, N.A.
Derivative liabilities:
Net amounts of liabilities presented in the consolidated balance sheet	203,779	169,085
Financial instruments	(200,338)	(165,224)
Net amount of liabilities in the consolidated balance sheet	3,441	3,861
Goldman Sachs
Derivative liabilities:
Net amounts of liabilities presented in the consolidated balance sheet	853,147
Financial instruments	(850,918)
Net amount of liabilities in the consolidated balance sheet	2,229
Other
Derivative liabilities:
Net amounts of liabilities presented in the consolidated balance sheet	2,642	21,988
Net amount of liabilities in the consolidated balance sheet	2,642	21,988
Interest rate lock commitments
Derivative liabilities:
Net amounts of liabilities presented in the consolidated balance sheet	1,280	2,935
Net amount of liabilities in the consolidated balance sheet	$ 1,280	$ 2,935