Stock-Based Compensation Stock Based Compensation (RSU) Details 2 (Details) (USD $)
3 Months Ended
Mar. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]  
RSUs granted 1,599,278
Restricted Stock Units (RSUs) [Member]  
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]  
Shares Outstanding, Beginning of Period 2,818,661
RSUs granted 1,599,278
RSUs Vested (210,353)
RSUs forfeited (40,020)
Shares Outstanding, End of Period 4,167,566
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Weighted Average Exercise Price [Roll Forward]  
Weighted Average Fair Value, Beginning of Period, USD per share 77.77
Weighted Average Fair Value, RSUs granted, USD per share 99.90
Weighted Average Fair Value, RSUs vested, USD per share 91.66
Weighted Average Fair Value, RSUs forfeited, USD per share 80.81
Weighted Average Fair Value, End of Period, USD per share 85.53