Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net income	$ 64,916	$ 46,209	$ 44,239
Other comprehensive income (loss), net of tax:
Amortization of prior service credits, net of taxes of $18, $20 and $20 for the years ended December 31, 2016, 2015 and 2014, respectively	(27)	(26)	(26)
Amortization of net actuarial losses, net of taxes of ($238), ($509) and ($330) for the years ended December 31, 2016, 2015 and 2014, respectively	330	669	370
Unrecognized actuarial gains (losses), net of taxes of ($367), ($465) and $2,880 for the years ended December 31, 2016, 2015 and 2014, respectively	235	615	(3,790)
Change in net unrealized (losses) gains on securities available for sale, net of taxes of $1,737, $2,911 and ($10,441) for the years ended December 31, 2016, 2015 and 2014, respectively	(2,452)	(3,818)	13,548
Reclassification adjustment for net gains included in net income, net of taxes of $638, $72 and $1,241 for the years ended December 31, 2016, 2015 and 2014, respectively	(886)	(95)	(1,634)
Total other comprehensive income (loss), net of tax	(2,800)	(2,655)	8,468
Comprehensive income	$ 62,116	$ 43,554	$ 52,707