CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
Net actuarial loss, tax expense (benefit)	$ (805)	$ (4,798)	$ (8,639)
Pension settlement expense, tax	1,256	1,246	2,565
Amortization of unrecognized net periodic benefit costs, tax	1,849	1,571	979
Change in unrealized income (loss) on interest rate swap, tax expense (benefit)	139	(126)	(226)
Change in foreign currency translation, tax expense (benefit)	$ 149	$ (451)	$ (137)