Summary of Significant Accounting Policies - NI per unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net Income Per Limited Partner Unit
Repurchased units not deemed outstanding	244,128				350,471				244,128	350,471
Net (loss) income attributable to Global Partners LP	$ 52,530	$ (14,080)	$ 6,413	$ 59,042	$ 18,554	$ 14,878	$ 2,374	$ 22,946	$ 103,905	$ 58,752	$ (199,412)
Declared distribution									65,794	63,316	63,316
Assumed allocation of undistributed net income (loss)									(38,111)	(4,564)	(262,728)
Assumed allocation of net (loss) income									$ 103,905	$ 58,752	$ (199,412)
Denominator:
Basic net income per limited partner unit	$ 1.49	$ (0.44)	$ 0.19	$ 1.74	$ 0.55	$ 0.44	$ 0.07	$ 0.68	$ 2.98	$ 1.74
Diluted net income per limited partner unit	$ 1.47	$ (0.44)	$ 0.19	$ 1.73	$ 0.55	$ 0.44	$ 0.07	$ 0.68	$ 2.95	$ 1.74
Common Limited Partners
Denominator:
Basic weighted average limited partner units outstanding									33,701,000	33,589,000	33,525,000
Diluted weighted average limited partner units outstanding									33,972,000	33,634,000	33,525,000
Basic net income per limited partner unit									$ 2.97	$ 1.74	$ (5.91)
Diluted net income per limited partner unit									$ 2.95	$ 1.74	$ (5.91)
Limited Partner Interest
Net Income Per Limited Partner Unit
Net (loss) income attributable to Global Partners LP									$ 102,872	$ 58,358	$ (198,076)
Declared distribution									65,019	62,892	62,892
Assumed allocation of undistributed net income (loss)									(37,853)	(4,534)	(260,968)
Assumed allocation of net (loss) income									102,872	$ 58,358	$ (198,076)
Denominator:
Basic weighted average limited partner units outstanding										33,589,000	33,525,000
Dilutive effect of phantom units										45,000
Diluted weighted average limited partner units outstanding										33,634,000	33,525,000
Basic net income per limited partner unit										$ 1.74	$ (5.91)
Diluted net income per limited partner unit										$ 1.74	$ (5.91)
Limited Partner Interest | Common Limited Partners
Net Income Per Limited Partner Unit
Assumed allocation of net (loss) income									$ 100,181
Denominator:
Basic weighted average limited partner units outstanding									33,701,000
Dilutive effect of phantom units									271,000
Diluted weighted average limited partner units outstanding									33,972,000
Basic net income per limited partner unit									$ 2.97
Diluted net income per limited partner unit									$ 2.95
Limited Partner Interest | Series A Preferred Limited Partners
Net Income Per Limited Partner Unit
Assumed allocation of net (loss) income									$ 2,691
General Partner, Global GP LLC
Net Income Per Limited Partner Unit
Net (loss) income attributable to Global Partners LP									1,033	$ 394	$ (1,336)
Declared distribution									439	424	424
Assumed allocation of undistributed net income (loss)									(258)	(30)	(1,760)
Assumed allocation of net (loss) income									697	$ 394	$ (1,336)
IDRs
Net Income Per Limited Partner Unit
Declared distribution									336
Assumed allocation of net (loss) income									$ 336