Goodwill (details) - Total Intangibles - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Other Intangible Assets disclosure
Intangible assets not subject to amortization	$ 227	$ 217
Total other intangible assets, gross carrying amount	513	427
Total other intangible assets, accumulated amortization	171	159
Total other intangible assets, net	342	268
Amortization expense for other intangible assets	13	$ 11	$ 26
Estimated intangible asset amortization expense, 2018	15
Estimated intangible asset amortization expense, 2019	14
Estimated intangible asset amortization expense, 2020	13
Estimated intangible asset amortization expense, 2021	12
Estimated intangible asset amortization expense, 2022	$ 11