Capital Stock (Tables)

12 Months Ended

Dec. 31, 2011

Capital Stock [Abstract]

Capital Stock

	Year Ended December 31,
	2011		2010		2009
Beginning balance		159,909,052		158,118,937		155,375,487
Shares issued in lieu of cash bonuses		—		—		184,926
Stock options/SARs exercised		862,774		991,988		1,384,861
Restricted stock grants		326,591		405,127		413,353
Issued for acreage purchases		—		380,229		743,737
Treasury shares		33,130		12,771		16,573
Ending balance		161,131,547		159,909,052		158,118,937