Long-Term Debt (Interest Expenses) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash payments for interest	$ 165,307	$ 155,854	$ 151,246
Accretion/amortization of discounts or premiums on loans	25,210	23,304	21,388
Accretion of discount on postretirement benefit obligations	315	433	657
Amortization of net deferred hedge losses (see Note I)	573	517	465
Amortization of capitalized loan fees	5,385	5,698	4,612
Net changes in accruals	(1,768)	11,999	3,762
Interest incurred	195,022	198,326	183,004
Less capitalized interest	(13,362)	(15,242)	(9,651)
Total interest expense	181,660	183,084	173,353
Derivative Obligations [Member]
Accretion of discount on derivative obligations		$ 521	$ 874