Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 17,201	$ 19,687
Unrealized gain (loss) on available-for-sale securities:
Unrealized gain arising during the period	1,300	15,568
Reclassification adjustment for gain included in net income	(1,960)	(9,738)
Total change in unrealized gain (loss) on available-for-sale securities	(660)	5,830
Total other comprehensive (loss) income	(660)	5,830
Comprehensive income	$ 16,541	$ 25,517