Changes in Accumulated Other Comprehensive Income (Loss) by Component (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 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			1,560	(38,100)
Amounts reclassified from accumulated other comprehensive income to the consolidated statements of income			5,700	8,423
Net current-period other comprehensive income (loss)	$ 2,882	$ (19,304)	7,260	(29,677)
Accumulated other comprehensive income (loss), Ending balance	(135,992)	(129,130)	(135,992)	(129,130)
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			(823)	(665)
Amounts reclassified from accumulated other comprehensive income to the consolidated statements of income			243	792
Net current-period other comprehensive income (loss)			(580)	127
Accumulated other comprehensive income (loss), Ending balance	(465)	(605)	(465)	(605)
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			283	1,412
Amounts reclassified from accumulated other comprehensive income to the consolidated statements of income			5,457	7,631
Net current-period other comprehensive income (loss)			5,740	9,043
Accumulated other comprehensive income (loss), Ending balance	(99,963)	(106,246)	(99,963)	(106,246)
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			2,100	(38,847)
Amounts reclassified from accumulated other comprehensive income to the consolidated statements of income			0	0
Net current-period other comprehensive income (loss)			2,100	(38,847)
Accumulated other comprehensive income (loss), Ending balance	$ (35,564)	$ (22,279)	$ (35,564)	$ (22,279)