CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Millions	Total	Common stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance as of beginning-of-year at Dec. 31, 2010		$ 8,124	$ 3,933	$ 748
Stock compensation/issued for benefit plans		2
Retirement of common stock/cancellation of shares		(62)
Cumulative effect from adoption of new accounting standards			(1,095)	103
Comprehensive income (loss)	336
Other comprehensive income (loss), net of tax	22			22
Net income (loss)	314		314
Retirement of common stock			(13)
Dividends declared: Common (2012 - $0.080; 2011 - $0.050)			(17)
Balance as of end-of-period at Mar. 31, 2011	12,059	8,064	3,122	873
Balance as of beginning-of-year at Dec. 31, 2011	13,238	7,590	2,969	2,679
Stock compensation/issued for benefit plans		8
Retirement of common stock/cancellation of shares		(150)
Cumulative effect from adoption of new accounting standards			0	0
Comprehensive income (loss)	188
Other comprehensive income (loss), net of tax	(57)			(57)
Net income (loss)	245		245
Retirement of common stock			0
Dividends declared: Common (2012 - $0.080; 2011 - $0.050)			(23)
Balance as of end-of-period at Mar. 31, 2012	$ 13,261	$ 7,448	$ 3,191	$ 2,622