Accumulated Other Comprehensive Income (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Balances	$ 8,514,000	$ 9,725,000	$ 12,354,000
Reclassification of net gains on hedging instruments from OCI to net income, net of tax	(4,302,000)	(1,188,000)	(1,188,000)
Reclassification of net gains in hedging instruments from OCI to net income, tax	458,000	0	0
Pension and postretirement medical liability adjustment, net of tax	(581,000)	(134,000)	(1,737,000)
Pension and postretirement medical liability adjustment, tax	155,000	75,000	1,088,000
Foreign currency translation	25,000	111,000	296,000
Balances	3,656,000	8,514,000	9,725,000
Accumulated Other Comprehensive Income [Member]
Reclassification of net gains on hedging instruments from OCI to net income, net of tax	(4,302,000)	(1,188,000)	(1,188,000)
Pension and postretirement medical liability adjustment, net of tax	(581,000)	(134,000)	(1,737,000)
Foreign currency translation	25,000	111,000	296,000
Net Unrealized Gains on Hedging Instruments
Balances	9,277,000	10,465,000	11,653,000
Reclassification of net gains on hedging instruments from OCI to net income, net of tax	(4,302,000)	(1,188,000)	(1,188,000)
Pension and postretirement medical liability adjustment, net of tax	0	0	0
Foreign currency translation	0	0	0
Balances	4,975,000	9,277,000	10,465,000
Pension and Other Benefits
Balances	(1,158,000)	(1,024,000)	713,000
Reclassification of net gains on hedging instruments from OCI to net income, net of tax	0	0	0
Pension and postretirement medical liability adjustment, net of tax	(581,000)	(134,000)	(1,737,000)
Foreign currency translation	0	0	0
Balances	(1,739,000)	(1,158,000)	(1,024,000)
Other
Balances	395,000	284,000	(12,000)
Reclassification of net gains on hedging instruments from OCI to net income, net of tax	0	0	0
Pension and postretirement medical liability adjustment, net of tax	0	0	0
Foreign currency translation	25,000	111,000	296,000
Balances	$ 420,000	$ 395,000	$ 284,000