Comprehensive Income Comprehensive Income (Loss) Accumulated Other Comprehensive Loss (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period Start	$ (23,581)	$ (19,164)
Comprehensive Income (Loss), Net of Tax	(9,297)	(4,417)	(381)
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period End	(32,878)	(23,581)	(19,164)
Cash Flow Hedging [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period Start	(12,437)	(9,462)
Comprehensive Income (Loss), Net of Tax	(1,363)	(2,975)
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period End	(13,800)	(12,437)
Equity Method Investee [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period Start	(2)	(66)
Comprehensive Income (Loss), Net of Tax	0	64
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period End	(2)	(2)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period Start	(11,142)	(9,636)
Comprehensive Income (Loss), Net of Tax	(7,934)	(1,506)
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period End	$ (19,076)	$ (11,142)