Income Taxes - Deferred Tax Assets (Liabilities) (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Accrued expenses	$ 1,307,000	$ 2,126,000
Net operating loss	6,614,000	4,765,000
Allowance for credit losses, net of bad debt charge-offs	85,700,000	10,415,000
Deferred compensation	3,489,000	3,616,000
State taxes	4,395,000	3,746,000
Loan discount	32,484,000	11,634,000
Stock-based compensation	4,618,000	3,535,000
Operating lease liabilities	24,463,000	13,334,000
Federal and state credit carryovers	3,750,000	416,000
Other	1,782,000	0
Total deferred tax assets	168,602,000	53,587,000
Deferred tax liabilities:
Operating lease right-of-use assets	(21,756,000)	(12,382,000)
Deferred FDIC gain	(108,000)	(228,000)
Core deposit intangibles	(21,828,000)	(22,415,000)
Loan origination costs	(5,176,000)	(4,828,000)
Depreciation	(6,551,000)	(1,814,000)
Unrealized gain on available for sale securities	(24,127,000)	(8,639,000)
Other	0	(4,652,000)
Total deferred tax liabilities	(79,546,000)	(54,958,000)
Valuation allowance	0	0
Net deferred tax asset (liabilities)	$ 89,056,000
Net deferred tax asset (liabilities)		$ (1,371,000)