Income Taxes Effective Tax Rate (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Apr. 01, 2015
Investments, Owned, Federal Income Tax Note [Line Items]
Effective Income Tax Rate Reconciliation, Percent	29.90%	32.90%	31.40%	33.10%
Deferred income tax expense (benefit)			$ 14
ARX Holding Corp. [Member]
Investments, Owned, Federal Income Tax Note [Line Items]
Ownership interest held prior to acquisition (percent)					5.00%