Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Comprehensive Income [Abstract]
Unrealized gains on available-for-sale securities, taxes	$ (2,855)	$ 3,848	$ (1,005)
Other Comprehensive Income Loss Transfers From Available For Sale To Held To Maturity, Tax	(32)	(172)	(193)
Other Comprehensive Income Loss Reclassification Adjustment For Sale Or Writedown Of Securities Included In Net Income Tax	$ 216	$ 465	$ 176