Consolidated Statements of Shareholders' Equity (unaudited) (USD $) In Millions	Total	Common Stock [Member]	Additional Paid in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Treasury Stock at Cost [Member]	Retained Earnings [Member]
Balance at Dec. 31, 2009	$ 6,157	$ 645	$ 2,260	$ (75)	$ (615)	$ 3,942
Net Income	673	0	0	0	0	673
Stock-based Compensation	40	0	40	0	0	0
Exercise of Stock Options	35	3	32	0	0	0
Tax Benefits Related to Exercise of Stock Options	19	0	19	0	0	0
Restricted Stock Awards, Net	0	2	(2)	0	0	0
Dividends	(95)	0	0	0	0	(95)
Changes in Treasury Stock, Net	(12)	0	0	0	(12)	0
Oil and Gas Cash Flow Hedges
Realized Amounts Reclassified Into Earnings	10	0	0	10	0	0
Interest Rate Cash Flow Hedges
Unrealized Change in Fair Value	(92)	0		(92)
Net Change in Other	2	0	0	2	0	0
Balance at Sep. 30, 2010	6,737	650	2,349	(155)	(627)	4,520
Balance at Dec. 31, 2010	6,848	651	2,385	(104)	(624)	4,540
Net Income	749	0	0	0	0	749
Stock-based Compensation	43	0	43	0	0	0
Exercise of Stock Options	32	2	30	0	0	0
Tax Benefits Related to Exercise of Stock Options	11	0	11	0	0	0
Restricted Stock Awards, Net	0	2	(2)	0	0	0
Dividends	(104)	0	0	0	0	(104)
Changes in Treasury Stock, Net	(16)	0	0	0	(16)	0
Interest Rate Cash Flow Hedges
Unrealized Change in Fair Value	15	0	0	15	0	0
Net Change in Other	4	0	0	4	0	0
Balance at Sep. 30, 2011	$ 7,582	$ 655	$ 2,467	$ (85)	$ (640)	$ 5,185