Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ (155,431,000)	$ (140,084,000)	$ (152,193,000)	$ (140,363,000)
Other comprehensive income before reclassifications	1,644,000	2,789,000	(4,492,000)	315,000
Amounts reclassified from accumulated other comprehensive income (net of tax $(1,918) and $(1,687))	3,011,000	2,647,000	5,909,000	5,400,000
Net current-period other comprehensive income	4,655,000	5,436,000	1,417,000	5,715,000
Ending balance	(150,776,000)	(134,648,000)	(150,776,000)	(134,648,000)
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Tax	(1,918,000)	(1,687,000)	(3,763,000)	(3,439,000)
Foreign Currency
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(5,852,000)	4,179,000	284,000	6,653,000
Other comprehensive income before reclassifications	1,644,000	2,789,000	(4,492,000)	315,000
Amounts reclassified from accumulated other comprehensive income (net of tax $(1,918) and $(1,687))	0	0	0	0
Net current-period other comprehensive income	1,644,000	2,789,000	(4,492,000)	315,000
Ending balance	(4,208,000)	6,968,000	(4,208,000)	6,968,000
Pension and Other Postretirement Benefits
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(149,579,000)	(144,263,000)	(152,477,000)	(147,016,000)
Other comprehensive income before reclassifications	0	0	0	0
Amounts reclassified from accumulated other comprehensive income (net of tax $(1,918) and $(1,687))	3,011,000	2,647,000	5,909,000	5,400,000
Net current-period other comprehensive income	3,011,000	2,647,000	5,909,000	5,400,000
Ending balance	$ (146,568,000)	$ (141,616,000)	$ (146,568,000)	$ (141,616,000)