Earnings Per Common Share - Narrative (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Sep. 30, 2014
Antidilutive securities excluded from computation of earnings per share
Repurchase and retirement of common stock (in shares)	3.2
Remaining number of shares authorized to be repurchased	24.6		50.0
Total consideration for repurchase of common stock including unpaid cash	$ 86
Dividends
Cash dividends per common share declared (in dollars per share)	$ 0.095	$ 0.090
Cash dividends per common share paid (in dollars per share)	$ 0.095	$ 0.090
Stock Options
Antidilutive securities excluded from computation of earnings per share
Antidilutive effect on computation of diluted earnings per common share (in shares)	1.0	8.0
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)	1.0