Goodwill and Other Intangible Assets - Goodwill Rollforward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Goodwill rollforward
Goodwill, beginning of year	$ 3,301	$ 3,225
Net change from business combinations	0	76
Goodwill, end of year	$ 3,301	$ 3,301