Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 42,244	$ 44,003	$ 75,548	$ 75,479
Other comprehensive income (loss), net of tax:
Changes in net prior service credit and actuarial losses	846	(133)	1,620	(544)
Change in fair value of derivatives	352	523	170	1,338
Foreign currency translation	11,324	3,160	(18,945)	(7,088)
Other comprehensive income (loss)	12,522	3,550	(17,155)	(6,294)
Comprehensive income	$ 54,766	$ 47,553	$ 58,393	$ 69,185