Loans - Summary of Allowance for Loan Losses by Portfolio Class and Category (Details) - Portfolio loans, net - USD ($) $ in Thousands		3 Months Ended
	Dec. 31, 2019	Mar. 31, 2021	Mar. 31, 2020
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2020		$ 136,671	$ 43,288
Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease)	$ 28,387
Provision for credit losses	(1,680)
Provision for Loan, Lease, and Other Losses		(503)	(21,695)
Charge-offs		(6,474)	(304)
Recoveries		827	801
Balance	43,288	131,527	92,187
Commercial and industrial
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2020		58,812	27,455
Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease)	6,494
Provision for credit losses	0
Provision for Loan, Lease, and Other Losses		(541)	(11,591)
Charge-offs		(3,739)	(63)
Recoveries		327	504
Balance	27,455	55,941	45,981
CRE - investor owned
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2020		32,062	5,935
Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease)	10,726
Provision for credit losses	(5)
Provision for Loan, Lease, and Other Losses		(3,381)	(3,224)
Charge-offs		(2,372)	(2)
Recoveries		34	14
Balance	5,935	33,105	19,892
CRE - owner occupied
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2020		17,012	4,873
Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease)	2,598
Provision for credit losses	(57)
Provision for Loan, Lease, and Other Losses		(3,226)	(1,994)
Charge-offs		(28)	0
Recoveries		9	69
Balance	4,873	20,219	9,477
Construction and land development
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2020		21,413	2,611
Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease)	5,183
Provision for credit losses	(217)
Provision for Loan, Lease, and Other Losses		7,091	(2,309)
Charge-offs		0	(31)
Recoveries		235	40
Balance	2,611	14,557	9,895
Residential real estate
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2020		4,585	1,280
Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease)	3,470
Provision for credit losses	(1,401)
Provision for Loan, Lease, and Other Losses		152	(2,011)
Charge-offs		(271)	(122)
Recoveries		143	157
Balance	1,280	4,305	5,395
Other
Allowance for Loan Losses [Roll Forward]
Balance at December 31, 2020		2,787	1,134
Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease)	(84)
Provision for credit losses	0
Provision for Loan, Lease, and Other Losses		(598)	(566)
Charge-offs		(64)	(86)
Recoveries		79	17
Balance	$ 1,134	$ 3,400	$ 1,547