Stockholders' Equity (Details) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended			3 Months Ended								12 Months Ended
	Oct. 31, 2014	Oct. 31, 2013	Nov. 30, 2012	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Class of Stock [Line Items]
Common stock, shares issued				51,500,000				50,500,000				51,500,000	50,500,000
Common stock, shares outstanding				48,300,000				48,700,000				48,300,000	48,700,000
Amount authorized for stock repurchase program				$ 600				$ 300				$ 600	$ 300	$ 150
Repurchased shares of treasury stock												1,407,729	1,722,991	31,008
Treasury stock activity												138	119	1
Dividends declared per share	$ 0.40	$ 0.20	$ 0.10	$ 0.40	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.10	$ 0.10	$ 0.10	$ 1.00	$ 0.50	$ 0.10
Dividends declared												49	25
Dividends declared - APIC														$ 5