Income Taxes - Additional Information (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Contingency [Line Items]
Unrecognized tax benefit, affect the effective tax rate	$ 10	$ 14	$ 11
Accruals for payment of interest and penalties associated with uncertain tax positions	3	4	3
Increase (decrease) in accruals for payment of interest and penalties associated with uncertain tax positions	(1)	1
Net deferred tax asset	$ 1,803	$ 1,474
Income, Taxes and Other Liabilities - Income Tax Reserve [Member]
Income Tax Contingency [Line Items]
Income tax examination, increase (decrease) in liability from prior year			183
Interest, Taxes and Other Liabilities - Accrued Interest [Member]
Income Tax Contingency [Line Items]
Income tax examination, increase (decrease) in liability from prior year			$ 120