Long-Term Debt And Other Long-Term Liabilities (Other Long-Term Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Long-Term Debt And Other Long-Term Liabilities [Abstract]
ARO liability	$ 96,446	$ 69,265	$ 56,404
Workers' compensation	17,026	17,566
Separation benefit plans	6,845	5,690
Gas balancing liability	3,263	3,263
Deferred compensation plan	2,463	2,368
Other liabilities	126,043	98,152
Less current portion	12,213	10,122
Total other long-term liabilities	$ 113,830	$ 88,030