Fair Value Measurements (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Apr. 30, 2014
National Pump    
Derivatives, Fair Value [Line Items]    
Contingent consideration   $ 76
Merger related costs    
Derivatives, Fair Value [Line Items]    
Change in contingent consideration (27)  
Diesel swap | Fixed price swap contracts    
Derivatives, Fair Value [Line Items]    
Fixed price swap contract (in gallons) 10,600,000  
Average contract price (in dollars per gallon) 3.22  
Average forward price (in dollars per gallon) 2.92  
Level 3 | National Pump | Accrued expenses and other liabilities    
Derivatives, Fair Value [Line Items]    
Contingent consideration 50  
First earn-out payment | National Pump    
Derivatives, Fair Value [Line Items]    
Contingent consideration 50  
Second earn-out payment | National Pump    
Derivatives, Fair Value [Line Items]    
Contingent consideration $ 0