Unfunded Loan Commitments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Credit Loss [Abstract]
Contractual obligation	$ 1,200,000		$ 1,200,000
Allowance
Beginning balance	19,367	$ 29,707	110,044	$ 2,481
Provision/New commitments - net	48,203	72,111	88,400	121,672
Other provision items	21,757	21,150	17,763	25,132
Transfer - funded loans	(24,555)	(37,010)	(151,435)	(179,085)
Ending balance	64,772	85,958	64,772	85,958
Unfunded Commitments
Beginning balance	457,453	449,807	1,673,018	1,910,603
Provision/New commitments - net	1,235,604	1,165,224	2,078,765	2,000,170
Other provision items	0	0	0	0
Transfer - funded loans	(531,361)	(495,989)	(2,590,087)	(2,791,731)
Ending balance	$ 1,161,696	$ 1,119,042	1,161,696	1,119,042
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