Condensed Consolidated Statements Of Equity (USD $) In Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income [Member]	Retained Earnings [Member]	Noncontrolling Interest [Member]	Total
Balances at Dec. 31, 2009	$ 1,745	$ 730,265	$ (36,363)	$ 121,336	$ (180,985)	$ 60,824	$ 696,822
Net income					116,794	11,119	127,913
Hedge derivative contract settlements reclassified into earnings from AOCI, net of income tax				(117,714)			(117,714)
Net change in derivative fair value, net of income tax				171,910			171,910
Currency translation adjustment				4,238			4,238
Issuance & vesting of stock compensation	8	15,333	(4,851)			858	11,348
Stock option exercises	2	1,600	(214)				1,388
Issuance of KGS common units		6,746				4,308	11,054
Distributions paid on KGS common units						(13,550)	(13,550)
Balances at Sep. 30, 2010	1,755	753,944	(41,428)	179,770	(64,191)	63,559	893,409
Balances at Dec. 31, 2010	1,755	714,869	(41,487)	130,187	254,084		1,059,408
Net income					66,515		66,515
Hedge derivative contract settlements reclassified into earnings from AOCI, net of income tax				(38,886)			(38,886)
Net change in derivative fair value, net of income tax				44,508			44,508
Currency translation adjustment				(25,118)			(25,118)
Issuance & vesting of stock compensation	13	15,462	(4,841)				10,634
Stock option exercises	1	732					733
Balances at Sep. 30, 2011	$ 1,769	$ 731,063	$ (46,328)	$ 110,691	$ 320,599		$ 1,117,794