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	$ 3,934	$ 748
Stock compensation/issued for benefit plans		9
Retirement of common stock/cancellation of shares		(195)
Cumulative effect from adoption of new accounting standards			(1,095)	103
Comprehensive income	993
Other comprehensive income (loss), net of tax	376			376
Net income (loss)	617		617
Retirement of common stock			(31)
Dividends declared: Common (2012 - $0.160; 2011 - $0.100)			(32)
Balance as of end-of-period at Jun. 30, 2011	12,558	7,938	3,393	1,227
Balance as of beginning-of-year at Dec. 31, 2011	13,238	7,590	2,969	2,679
Stock compensation/issued for benefit plans		20
Retirement of common stock/cancellation of shares		(300)
Cumulative effect from adoption of new accounting standards			0	0
Comprehensive income	1,269
Other comprehensive income (loss), net of tax	700			700
Net income (loss)	569		569
Retirement of common stock			0
Dividends declared: Common (2012 - $0.160; 2011 - $0.100)			(45)
Balance as of end-of-period at Jun. 30, 2012	$ 14,182	$ 7,310	$ 3,493	$ 3,379