Consolidated statements of comprehensive income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 9,753	$ 14,599
Other comprehensive income, net of tax:
Net change in unrealized (loss) gain in available-for-sale securities, net of taxes of $354 and $538	550	8,206
Reclassification adjustment for gain on sale of securities included in net income, net of tax expense of $0 and $157	(1)	(1,243)
Comprehensive income	$ 10,302	$ 21,562