Accumulated Other Comprehensive Loss (Details) (USD $)	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Accumulated Other Comprehensive Loss [Roll Forward]
Beginning balance	$ (80,420,000)		$ (115,930,000)		$ (80,923,000)		$ (116,840,000)
Other comprehensive income before reclassifications	0		509,000		0		464,000
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	59,000	[1]	103,000	[1]	118,000	[1]	207,000	[1]
Amounts reclassified from accumulated other comprehensive loss, Actuarial loss	444,000	[2]	1,105,000	[2]	888,000	[2]	1,956,000	[2]
Amounts reclassified from accumulated other comprehensive loss, tax	(2,027,000)		711,000		(2,176,000)		(4,239,000)
Ending balance	(79,917,000)		(114,213,000)		(79,917,000)		(114,213,000)
Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Loss [Roll Forward]
Net current-period other comprehensive income	503,000		1,717,000		1,006,000		2,627,000
Gains and Losses on Derivatives
Accumulated Other Comprehensive Loss [Roll Forward]
Beginning balance			(950,000)				(1,009,000)
Other comprehensive income before reclassifications			509,000				464,000
Ending balance			(338,000)				(338,000)
Gains and Losses on Derivatives | Interest rate swaps
Accumulated Other Comprehensive Loss [Roll Forward]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax			103,000	[1]			207,000	[1]
Gains and Losses on Derivatives | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Loss [Roll Forward]
Amounts reclassified from accumulated other comprehensive loss, Actuarial loss			0	[2]			0	[2]
Net current-period other comprehensive income			612,000				671,000
Gains and Losses on Derivatives | Reclassification out of Accumulated Other Comprehensive Income | Interest rate swaps
Accumulated Other Comprehensive Loss [Roll Forward]
Amounts reclassified from accumulated other comprehensive loss, tax			63,000				126,000
Defined Benefit Pension Items
Accumulated Other Comprehensive Loss [Roll Forward]
Beginning balance	(79,933,000)		(115,337,000)		(80,377,000)		(116,188,000)
Other comprehensive income before reclassifications	0		0		0		0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	[1]	0	[1]	0	[1]	0	[1]
Ending balance	(79,489,000)		(114,232,000)		(79,489,000)		(114,232,000)
Defined Benefit Pension Items | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Loss [Roll Forward]
Amounts reclassified from accumulated other comprehensive loss, Actuarial loss	444,000	[2]	1,105,000	[2]	888,000	[2]	1,956,000	[2]
Amounts reclassified from accumulated other comprehensive loss, tax	280,000		1,001,000		560,000		1,299,000
Net current-period other comprehensive income	444,000		1,105,000		888,000		1,956,000
Other
Accumulated Other Comprehensive Loss [Roll Forward]
Beginning balance	172,000		357,000		172,000		357,000
Other comprehensive income before reclassifications	0		0		0		0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	[1]	0	[1]	0	[1]	0	[1]
Ending balance	172,000		357,000		172,000		357,000
Other | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Loss [Roll Forward]
Amounts reclassified from accumulated other comprehensive loss, Actuarial loss	0	[2]	0	[2]	0	[2]	0	[2]
Net current-period other comprehensive income	0		0		0		0
Gain or Loss on Derivatives [Member]
Accumulated Other Comprehensive Loss [Roll Forward]
Beginning balance	(659,000)				(718,000)
Other comprehensive income before reclassifications	0				0
Ending balance	(600,000)				(600,000)
Gain or Loss on Derivatives [Member] | Interest rate swaps
Accumulated Other Comprehensive Loss [Roll Forward]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	59,000	[1]			118,000	[1]
Gain or Loss on Derivatives [Member] | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Loss [Roll Forward]
Amounts reclassified from accumulated other comprehensive loss, Actuarial loss	0	[2]			0	[2]
Net current-period other comprehensive income	59,000				118,000
Gain or Loss on Derivatives [Member] | Reclassification out of Accumulated Other Comprehensive Income | Interest rate swaps
Accumulated Other Comprehensive Loss [Roll Forward]
Amounts reclassified from accumulated other comprehensive loss, tax	$ 37,000				$ 74,000

[1] (a) Interest rate swap is included in interest expense in the Condensed Consolidated Statements of Operations

[2] (b) Actuarial loss is included in defined benefit pension plan expense in the Condensed Consolidated Statements of Operations