Changes in Accumulated Other Comprehensive Income (Loss) by Component (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
Accumulated other comprehensive income (loss), Beginning balance			$ (143,252)	$ (99,453)
Other comprehensive (loss) income before reclassifications to consolidated statements of income			592	(16,019)
Amounts reclassified from accumulated other comprehensive income to the consolidated statements of income			3,785	5,646
Net current-period other comprehensive income (loss)	$ (17,507)	$ 25,611	4,377	(10,373)
Accumulated other comprehensive income (loss), Ending balance	(138,875)	(109,826)	(138,875)	(109,826)
Gains and Losses on Cash Flow Hedges
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
Accumulated other comprehensive income (loss), Beginning balance			115	(732)
Other comprehensive (loss) income before reclassifications to consolidated statements of income			(571)	(249)
Amounts reclassified from accumulated other comprehensive income to the consolidated statements of income			141	550
Net current-period other comprehensive income (loss)			(430)	301
Accumulated other comprehensive income (loss), Ending balance	(315)	(431)	(315)	(431)
Pension and Other Postretirement Benefit Items
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
Accumulated other comprehensive income (loss), Beginning balance			(105,703)	(115,289)
Other comprehensive (loss) income before reclassifications to consolidated statements of income			53	355
Amounts reclassified from accumulated other comprehensive income to the consolidated statements of income			3,644	5,096
Net current-period other comprehensive income (loss)			3,697	5,451
Accumulated other comprehensive income (loss), Ending balance	(102,006)	(109,838)	(102,006)	(109,838)
Foreign Currency Items
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
Accumulated other comprehensive income (loss), Beginning balance			(37,664)	16,568
Other comprehensive (loss) income before reclassifications to consolidated statements of income			1,110	(16,125)
Amounts reclassified from accumulated other comprehensive income to the consolidated statements of income			0	0
Net current-period other comprehensive income (loss)			1,110	(16,125)
Accumulated other comprehensive income (loss), Ending balance	$ (36,554)	$ 443	$ (36,554)	$ 443