Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 5,427	$ 12,018
Other comprehensive income:
Unrealized (loss) gain on debt securities (net of tax benefit of $85 and tax expense of $43 in 2018 and 2017, respectively)	(321)	62
Accretion of unrealized loss on debt securities reclassified to held-to-maturity (net of tax expense of $57 and $116 in 2018 and 2017, respectively)	216	168
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	1	0
Total comprehensive income	$ 5,323	$ 12,248