Loans and Allowance for Credit Losses Activity in the Allowance for Credit Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 166,209	$ 169,410	$ 176,084
Loans charged off	30,557
Recoveries of loans previously charged off	21,020
Net loans recovered (charged off)	(9,537)
Provision for credit losses	76,920
Ending balance	291,940	166,209	169,410
Cumulative Effect, Period of Adoption, Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	58,348
Ending balance		58,348
Off-Balance Sheet
Allowance for Loan and Lease Losses [Roll Forward]
Provision for credit losses	840	2,600	8,900
Ending balance	14,400
Off-Balance Sheet | Cumulative Effect, Period of Adoption, Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ (6,300)	2,700
Ending balance		$ (6,300)	$ 2,700