Accumulated Other Comprehensive Income by Component (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Accumulated Other Comprehensive Income [Line Items]
Beginning balance, accumulated other comprehensive income			$ 2,317
Other comprehensive income before reclassifications	86	46	135	(1)
Amounts reclassified from accumulated other comprehensive income	(183)	(191)	(366)	(374)
Total Other Comprehensive Loss	(97)	(145)	(231)	(170)
Ending balance, accumulated other comprehensive income	2,086		2,086
Gains on Derivative Instruments Designated as Cash Flow Hedges
Accumulated Other Comprehensive Income [Line Items]
Beginning balance, accumulated other comprehensive income			4,243
Other comprehensive income before reclassifications			0
Amounts reclassified from accumulated other comprehensive income			(366)
Total Other Comprehensive Loss			(366)
Ending balance, accumulated other comprehensive income	3,877		3,877
Pension and Postretirement Medical Plans
Accumulated Other Comprehensive Income [Line Items]
Beginning balance, accumulated other comprehensive income			(2,292)
Other comprehensive income before reclassifications			0
Amounts reclassified from accumulated other comprehensive income			0
Total Other Comprehensive Loss			0
Ending balance, accumulated other comprehensive income	(2,292)		(2,292)
Foreign Currency Translation
Accumulated Other Comprehensive Income [Line Items]
Beginning balance, accumulated other comprehensive income			366
Other comprehensive income before reclassifications			135
Amounts reclassified from accumulated other comprehensive income			0
Total Other Comprehensive Loss			135
Ending balance, accumulated other comprehensive income	$ 501		$ 501