Stock Repurchase Programs - Summary of Stock Repurchase Activity (Details) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2016 USD ($) $ / shares shares
Equity [Abstract]
Shares Repurchased (in shares) | shares	42
Average Price per Share (in usd per share) | $ / shares	$ 23.67
Value of Shares Repurchased	$ 1,000
Shares Repurchased, Remaining Amount Authorized
Beginning balance	1,836
Repurchase of shares of common stock	(1,000)
Ending balance	$ 836