Goodwill and Intangible Assets - Schedule of Intangible Assets Other than Goodwill (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, Gross Amount	$ 93,538	$ 59,987
Finite-lived intangible assets, Accumulated Amortization	19,883	12,982
Intangible assets, Net Amount	73,655	47,005
Wholesale Fuel Supply Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, Gross Amount	56,145	25,736
Finite-lived intangible assets, Accumulated Amortization	12,477	9,059
Finite-lived intangible assets, Net Carrying Amount	43,668	16,677
Wholesale Fuel Distribution Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, Gross Amount	28,360	26,180
Finite-lived intangible assets, Accumulated Amortization	4,336	2,282
Finite-lived intangible assets, Net Carrying Amount	24,024	23,898
Trademarks [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, Gross Amount	634	634
Finite-lived intangible assets, Accumulated Amortization	300	78
Finite-lived intangible assets, Net Carrying Amount	334	556
Covenant Not to Compete [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, Gross Amount	3,228	2,676
Finite-lived intangible assets, Accumulated Amortization	719	253
Finite-lived intangible assets, Net Carrying Amount	2,509	2,423
Below Market Leases [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, Gross Amount	5,171	4,761
Finite-lived intangible assets, Accumulated Amortization	2,051	1,310
Finite-lived intangible assets, Net Carrying Amount	$ 3,120	$ 3,451