Stock Repurchase Programs - Summary of Stock Repurchase Activity (Details) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2016 USD ($) $ / shares shares
Equity [Abstract]
Shares Repurchased | shares	80,000,000
Average Price per Share (in usd per share) | $ / shares	$ 25.12
Value of Shares Repurchased	$ 2,000
Shares Repurchased, Remaining Amount Authorized
Beginning balance	1,836
Authorization of additional plan in July 2016	2,500
Repurchase of shares of common stock	(2,000)
Ending balance	$ 2,336
Treasury shares retired | shares	0