Goodwill and Other Intangible Assets - Goodwill Rollforward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Goodwill rollforward
Goodwill, beginning of year	$ 3,225	$ 3,225
Net change from business combinations	0	0
Goodwill, end of year	$ 3,225	$ 3,225