Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, Percent	32.30%		34.50%	28.70%	33.30%
Current State and Local Tax Expense (Benefit)	$ 4	$ 14
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	3	$ 4
Deferred Tax Assets, Net	198			$ 198		$ 250
Operating Loss Carryforwards, Valuation Allowance	$ 4			$ 4