Stockholders' Equity - Additional Information (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Jul. 30, 2014
Class of Stock [Line Items]
Dividends declared per common share	$ 0.05	$ 0.05
Stock Repurchase Program, Authorized Amount			$ 1,400,000,000
Repurchases of common stock	63,000,000	64,000,000
Shares repurchased during period	2,913,720
Stock Repurchase Program, Remaining Authorized Repurchase Amount	248,000,000
Common Stock [Member]
Class of Stock [Line Items]
Dividends accrued	$ 8,000,000