Changes in Accumulated Other Comprehensive Loss by Component (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013
Changes to accumulated other comprehensive loss by component
Balance at the beginning of the period	$ (7,084)
Other comprehensive earning (loss) before reclassifications	(20)
Amounts reclassified from accumulated other comprehensive loss	628
Balance at the end of the period	(6,476)
Unrealized Net Loss on Interest Rate Swap
Changes to accumulated other comprehensive loss by component
Balance at the beginning of the period	(344)
Other comprehensive earning (loss) before reclassifications	(20)
Amounts reclassified from accumulated other comprehensive loss	140
Balance at the end of the period	(224)
Retiree Health Obligation
Changes to accumulated other comprehensive loss by component
Balance at the beginning of the period	1,063
Amounts reclassified from accumulated other comprehensive loss	(81)
Balance at the end of the period	982
Pension Obligation
Changes to accumulated other comprehensive loss by component
Balance at the beginning of the period	(7,803)
Amounts reclassified from accumulated other comprehensive loss	569
Balance at the end of the period	$ (7,234)