Employee Stock Ownership Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Employee Stock Ownership Plan (ESOP), Shares in ESOP	23,636,184	26,137,798
Outstanding Borrowings from the Company	$ 12
Common shares released and allocated to participant accounts (in shares)	17,690,600
Common shares available for future allocation to participant accounts (in shares)	5,945,584
Annual ESOP expense	$ 0	$ 2	$ 0
Dividends paid by the Company on shares held by the ESOP	38	40	41
Company contributions to the ESOP	$ 0	$ 2	$ 0