Schedule of Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of Goodwill [Abstract]
Goodwill Deductible For Federal Income Tax Purpose	$ 50
Goodwill	313	$ 302	$ 301
Goodwill, Acquired During Period	$ 11	$ 1