Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 24,071	$ 12,817	$ 45,200	$ 32,514
Other comprehensive income:
Unrealized (loss) gain on debt securities (net of tax benefit of $46 and $207 in 2018, and net of tax benefit of $8 and net of tax expense of $50 in 2017, respectively)	(179)	(12)	(772)	72
Accretion of unrealized (gain) loss on debt securities reclassified to held-to-maturity (net of tax expense of $336 and $854 in 2018, and net of tax expense of $122 and $365 in 2017, respectively)	(110)	176	1,836	528
Reclassification adjustment for gains included in net income (net of tax expense of $0 and $53 in 2018)	0	0	195	0
Total comprehensive income	$ 23,782	$ 12,981	$ 46,459	$ 33,114