Goodwill and Other Intangible Assets (details) - Other Intangible Assets - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Goodwill and Other Intangible Assets disclosure
Intangible assets subject to amortization, gross carrying amount	$ 285		$ 285		$ 210
Intangible assets subject to amortization, accumulated amortization	167		167		159
Intangible assets subject to amortization, net	118		118		51
Intangible assets not subject to amortization	227		227		217
Total other intangible assets, gross carrying amount	512		512		427
Total other intangible assets, net	345		345		$ 268
Amortization expense of intangible assets	4	$ 3	9	$ 8
Estimated intangible asset amortization expense, remainder of 2017	4		4
Estimated intangible asset amortization expense, 2018	15		15
Estimated intangible asset amortization expense, 2019	14		14
Estimated intangible asset amortization expense, 2020	13		13
Estimated intangible asset amortization expense, 2021	$ 12		$ 12