Earnings Per Common Share (Details 2) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Antidilutive securities excluded from computation of earnings per share
Total consideration for repurchase of common stock including unpaid cash			$ 207
Repurchase and retirement of common stock (in shares)			7,900
Remaining number of shares authorized to be repurchased	37,100		37,100
Dividends
Cash dividends per common share paid (in dollars per share)	$ 0.090	$ 0.075	$ 0.180	$ 0.15
Cash dividends per common share declared (in dollars per share)	$ 0.09	$ 0.09	$ 0.18	$ 0.165
Stock Options
Antidilutive securities excluded from computation of earnings per share
Antidilutive effect on computation of diluted earnings per common share (in shares)	6,000	11,000	9,000	11,000
Long-term stock awards
Antidilutive securities excluded from computation of earnings per share
Repurchase and retirement of common stock to offset the dilutive impact of stock awards (in shares)			720