Unfunded Loan Commitments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Credit Loss [Abstract]
Contractual obligation	$ 2,000,000		$ 2,000,000
Allowance
Beginning balance	64,772	$ 85,958	110,044	$ 2,481
Provision/New commitments - net	129,904	157,337	218,304	279,008
Other provision items	15,068	(28,047)	32,831	(2,914)
Transfer - funded loans	(110,613)	(100,470)	(262,048)	(279,555)
Ending balance	99,131	114,778	99,131	114,778
Unfunded Commitments
Beginning balance	1,161,696	1,119,042	1,673,018	1,910,603
Provision/New commitments - net	2,885,024	2,542,390	4,963,789	4,542,560
Other provision items	0	0	0	0
Transfer - funded loans	(2,083,128)	(1,890,305)	(4,673,215)	(4,682,036)
Ending balance	$ 1,963,592	$ 1,771,127	1,963,592	1,771,127
Cumulative Effect, Period Of Adoption, Adjustment
Allowance
Beginning balance			0	115,758
Unfunded Commitments
Beginning balance			0	0
Cumulative Effect, Period Of Adoption, Adjusted Balance
Allowance
Beginning balance			110,044	118,239
Unfunded Commitments
Beginning balance			$ 1,673,018	$ 1,910,603