Income Taxes (Income Tax Payables and Income Tax Receivables) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income taxes receivable—current	$ 145	$ 166
Total income taxes receivable	145	166
Income taxes payable—current	149	264
Income taxes payable—noncurrent	22	35
Total income taxes payable	$ 171	$ 299