Loans and Allowance for Credit Losses Activity in the Allowance for Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 280,259	$ 257,471	$ 291,940	$ 166,209	$ 166,209
Loans charged off	9,522	8,047	17,724	22,050
Recoveries of loans previously charged off	2,568	3,926	4,589	6,813
Total net (charge-offs) recoveries	(6,954)	(4,121)	(13,135)	(15,237)
Provision for credit losses	(3,500)	19,570	(9,000)	63,600
Ending balance	269,805	272,920	269,805	272,920	291,940
Cumulative Effect, Period of Adoption, Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	0	0	0	58,348	58,348
Ending balance					0
Off-Balance Sheet
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				12,600	$ 12,600
Provision for credit losses	$ (500)	$ (2,600)	$ 400	$ 1,200