Fair Value Measurements (Narrative) (Details) gal in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2015 USD ($) $ / gal gal	Dec. 31, 2014 USD ($)
Merger related costs
Derivatives, Fair Value [Line Items]
Change in contingent consideration	$ (26)
Merger related costs | National Pump
Derivatives, Fair Value [Line Items]
Change in contingent consideration	$ (26)
Diesel swap | Fixed price swap contracts
Derivatives, Fair Value [Line Items]
Fixed price swap contract (in gallons) | gal	9.5
Average contract price (in dollars per gallon) | $ / gal	3.06
Average forward price (in dollars per gallon) | $ / gal	2.65
Level 3 | National Pump | Accrued expenses and other liabilities
Derivatives, Fair Value [Line Items]
Contingent consideration	$ 0	$ 78