Securities - Carrying Amount and Fair Value of Investment Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Schedule Of Available For Sale Securities [Line Items]
Investment securities available-for-sale	$ 540,045	$ 380,490
Amortized Cost	524,619	382,696
Unrealized Gains	16,361	1,388
Unrealized Losses	935	3,594
Fair Value	540,045	380,490
US Treasury Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	4,988	4,969
Unrealized Gains	27
Unrealized Losses		3
Investment securities available-for-sale	5,015	4,966
US government agencies
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	22,444	31,121
Unrealized Gains	335	48
Unrealized Losses		225
Investment securities available-for-sale	22,779	30,944
Mortgage-backed securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	488,694	345,606
Unrealized Gains	15,530	1,340
Unrealized Losses	927	3,365
Investment securities available-for-sale	503,297	343,581
Municipal bonds
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	8,493	1,000
Unrealized Gains	469
Unrealized Losses	8	1
Investment securities available-for-sale	$ 8,954	$ 999

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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