Employee Stock Ownership Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Shares in ESOP (in shares)	21,082,162	23,636,184
Outstanding borrowings in the ESOP	$ 7
Common shares released and allocated to participant accounts (in shares)	16,409,918
Common shares available for future allocation to participant accounts (in shares)	4,672,244
Annual ESOP expense	$ 0	$ 0	$ 2
Dividends paid by the Company on shares held by the ESOP	35	38	40
Company contributions to the ESOP	$ 0	$ 0	$ 2