Long-Term Debt And Other Long-Term Liabilities (Other Long-Term Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Long-term debt and other long-term liabilites [Abstract]
ARO liability	$ 98,297	$ 100,567	$ 133,657
Capital lease obligations	22,466	25,876
Workers' compensation	16,551	17,997
Separation benefit plans	9,886	11,276
Gas balancing liability	5,047	3,623
Deferred compensation plan	4,244	4,055
Other	410	410
Other liabilities	156,901	163,804
Less current portion	16,560	15,019
Total other long-term liabilities	$ 140,341	$ 148,785