Premises and Equipment - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property Plant And Equipment [Abstract]
Depreciation and leasehold amortization expense		$ 1,800,000	$ 989,000	$ 686,000
Operating leases expire at various dates through year	2028
Total rental expense, recognized on straight-line basis	$ 6,100,000	$ 2,700,000	$ 1,500,000
Operating lease expiration date	2018-05
Sub-lease income	$ 197,000