Fair Value Measurements (Narrative) (Details) gal in Millions, $ in Millions	6 Months Ended
Jun. 30, 2015 USD ($) $ / gal gal	Dec. 31, 2014 USD ($)
Merger related costs
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	10.8
Average contract price (in dollars per gallon) \| $ / gal	3.13
Average forward price (in dollars per gallon) \| $ / gal	3.02
Level 3 \| National Pump \| Accrued expenses and other liabilities
Derivatives, Fair Value [Line Items]
Contingent consideration	$ 0	$ 78

Amount of increase (decrease) in the value of a contingent consideration liability, including, but not limited to, differences arising upon settlement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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Amount of liability recognized arising from contingent consideration in a business combination.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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-Section 35

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

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The average forward price on the group of price risk forward or futures contracts, such as gas futures contracts.

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Nominal volume used to calculate payments on a derivative instrument.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Specified interest rate, security price, commodity price, foreign exchange rate, index of prices or rates for a derivative contract measured in volume but not the derivative contract itself.

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