Consolidated Statements Of Stockholders' Equity (USD $) In Millions	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Balance as of beginning-of-year at Dec. 31, 2011	$ 7,590	$ 2,831	$ 2,680
Stock compensation/issued for benefit plans	8
Retirement of common stock/cancellation of shares	(150)
Net income (loss)		243		243
Dividends declared: Common (2013 - $0.120; 2012 - $0.080)		(23)
Other comprehensive income (loss), net of tax			(57)	(57)
Balance as of end-of-period at Mar. 31, 2012	7,448	3,051	2,623	13,122
Balance as of beginning-of-year at Dec. 31, 2012	7,121	4,044	3,808	14,973
Stock compensation/issued for benefit plans	10
Retirement of common stock/cancellation of shares	(88)	(12)
Net income (loss)		239		239
Dividends declared: Common (2013 - $0.120; 2012 - $0.080)		(33)
Other comprehensive income (loss), net of tax			(227)	(227)
Balance as of end-of-period at Mar. 31, 2013	$ 7,043	$ 4,238	$ 3,581	$ 14,862