Income Taxes (Details 3) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets
Deferred and refundable income taxes	$ 101	$ 89
Deferred tax liabilities
Deferred income taxes and other liabilities	(579)	(939)
Deferred income taxes, net	$ (478)	$ (850)