Shareholders' Equity And Net Income Per Share Dividends (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended			6 Months Ended
	Aug. 15, 2018	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Cash dividends per share		$ 0.17	$ 0.17	$ 0	$ 0.34	$ 0.00
Payments of Cash Dividends		$ 15	$ 15		$ 30
Subsequent Event
Cash dividends per share	$ 0.17