Stock-Based Compensation (PBRSU Weighted Average Assumptions) (Details) - PBRSU [Member]		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield		0.00%	0.00%
Risk-free interest rate	[1]	0.99%	0.93%
Expected volatility	[2]	25.12%	24.01%
Average total stockholder return	[2]	1.48%	8.37%

[1] The risk-free interest rate for the periods within the contractual term of the PBRSUs is based on the U.S. Treasury yield curve in effect at the time of the grant.

[2] The expected volatility and average total stockholder return are measures of the amount by which a stock price has fluctuated or is expected to fluctuate based primarily on our and our peers' historical data.