Share Repurchase Programs and Dividends - Dividends (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended				6 Months Ended
	Apr. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Equity [Abstract]
Cash dividends declared per common share (in dollars per share)	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.20	$ 0.20
Payments of dividends	$ 44					$ 90