Loans and Allowance for Credit Losses for Loans - Summary of Provision for Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Receivables [Abstract]
Provision for loan losses	$ 30,833	$ 8,757	$ 105,709	$ 20,319
Provision for unfunded credit commitments	187	(57)	350	(1,519)
Total provision for credit losses for loans	$ 31,020	$ 8,700	$ 106,059	$ 18,800