Summary of Significant Accounting Policies - NI per unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net Income Per Limited Partner Unit
Repurchased units not deemed outstanding	128,170				244,128				128,170	244,128
Net income attributable to Global Partners LP	$ (828)	$ 15,080	$ 14,489	$ 7,126	$ 52,530	$ (14,080)	$ 6,413	$ 59,042	$ 35,867	$ 103,905	$ 58,752
Declared distribution									71,988	65,794	63,316
Assumed allocation of undistributed net income (loss)									36,121	38,111	(4,564)
Assumed allocation of net income									$ 35,867	$ 103,905	$ 58,752
Denominator:
Basic net income per limited partner unit (in dollars per unit)	$ (0.08)	$ 0.38	$ 0.37	$ 0.15	$ 1.49	$ (0.44)	$ 0.19	$ 1.74	$ 0.82	$ 2.98
Diluted net income per limited partner unit (in dollars per unit)	$ (0.08)	$ 0.38	$ 0.36	$ 0.15	$ 1.47	$ (0.44)	$ 0.19	$ 1.73	$ 0.81	$ 2.95
Common Limited Partners
Denominator:
Basic weighted average limited partner units outstanding									33,810,000	33,701,000	33,589,000
Diluted weighted average limited partner units outstanding									34,339,000	33,972,000	33,634,000
Basic net income per limited partner unit (in dollars per unit)									$ 0.82	$ 2.97	$ 1.74
Diluted net income per limited partner unit (in dollars per unit)									$ 0.81	$ 2.95	$ 1.74
Limited Partner Interest
Net Income Per Limited Partner Unit
Net income attributable to Global Partners LP									$ 34,488	$ 102,872	$ 58,358
Declared distribution									70,372	65,019	62,892
Assumed allocation of undistributed net income (loss)									35,884	37,853	(4,534)
Assumed allocation of net income									34,488	$ 102,872	$ 58,358
Denominator:
Basic weighted average limited partner units outstanding										33,701,000	33,589,000
Dilutive effect of phantom units										271,000	45,000
Diluted weighted average limited partner units outstanding										33,972,000	33,634,000
Basic net income per limited partner unit (in dollars per unit)										$ 2.97	$ 1.74
Diluted net income per limited partner unit (in dollars per unit)										$ 2.95	$ 1.74
Limited Partner Interest | Common Limited Partners
Net Income Per Limited Partner Unit
Assumed allocation of net income									$ 27,760	$ 100,181
Denominator:
Basic weighted average limited partner units outstanding									33,810,000
Dilutive effect of phantom units									529,000
Diluted weighted average limited partner units outstanding									34,339,000
Basic net income per limited partner unit (in dollars per unit)									$ 0.82
Diluted net income per limited partner unit (in dollars per unit)									$ 0.81
Limited Partner Interest | Series A Preferred Limited Partners
Net Income Per Limited Partner Unit
Assumed allocation of net income									$ 6,728	2,691
General Partner, Global GP LLC
Net Income Per Limited Partner Unit
Net income attributable to Global Partners LP									1,379	1,033	$ 394
Declared distribution									477	439	424
Assumed allocation of undistributed net income (loss)									237	258	(30)
Assumed allocation of net income									240	697	$ 394
IDRs
Net Income Per Limited Partner Unit
Declared distribution									1,139	336
Assumed allocation of net income									$ 1,139	$ 336