Consolidated statements of comprehensive income (loss) (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net change in unrealized gain (loss) in available for sale securities, tax	$ 170	$ 38	$ 1,577	$ 807
Reclassification adjustment for gain (loss) on sale of securities included in net income, tax	100	57	111	298
Net change in unrealized gain in hedging activities, tax	$ 111	$ 0	$ 111	$ 0