CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other comprehensive income (loss):
Net unrealized gain (loss) on available-for-sale securities, tax expense (benefit)	$ (1,242)	$ (169)	$ 1,476
Net realized gain on sale of available-for-sale securities included in net income, tax expense (benefit)	370	168	51
Change in nonqualified pension plan unrecognized net gain (loss) and unrecognized prior service cost, tax expense (benefit)	$ 128	$ 55	$ (133)