CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
Net actuarial loss, tax expense (benefit)	$ 450	$ (64)	$ 1,349	$ (999)
Pension settlement expense, tax	111	290	279	1,051
Amortization of unrecognized net periodic benefit costs, tax	171	352	390	753
Change in unrealized income (loss) on interest rate swap, tax expense (benefit)	(7)	52	275	140
Change in foreign currency translation, tax expense (benefit)	$ (78)	$ (134)	$ (103)	$ (58)