Income Taxes (Income Tax Payables and Income Tax Receivables) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income taxes receivable—current	$ 167	$ 217
Total income taxes receivable	167	217
Income taxes payable—current	264	299
Income taxes payable—noncurrent	35	2
Total income taxes payable	$ 299	$ 301