Accumulated Other Comprehensive Income (Tables)

3 Months Ended

Mar. 31, 2019

Accumulated Other Comprehensive Income [Abstract]

Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]

The following table presents the changes in the components of accumulated other comprehensive loss for the periods shown (in thousands):

	Three Months Ended March 31, 2019
	Currency Translation			Employee Benefit Plans			Total			Attributable to Noncontrolling Interest			Attributable to SemGroup
December 31, 2018	$	(45,816	)	$	(5,431	)	$	(51,247	)	$	—		$	(51,247	)
Currency translation adjustment, net of income tax benefit of $1,170	(3,735		)	—			(3,735		)	5,612			(9,347		)
Reclassification of certain tax effects from adoption of ASU 2018-02	(10,884		)	—			(10,884		)	—			(10,884		)
Changes related to benefit plans, net of income tax expense of $143	—			386			386			(32		)	418
March 31, 2019	$	(60,435	)	$	(5,045	)	$	(65,480	)	$	5,580		$	(71,060	)

	Three Months Ended March 31, 2018
	Currency Translation			Employee Benefit Plans			Total
December 31, 2017	$	(51,014	)	$	(2,787	)	$	(53,801	)
Currency translation adjustment, net of income tax benefit of $2,950	(9,137		)	—			(9,137		)
Currency translation adjustment reclassified to gain on disposal, net of income tax expense of $8,818	27,305			—			27,305
Changes related to benefit plans, net of income tax expense of $1	—			3			3
March 31, 2018	$	(32,846	)	$	(2,784	)	$	(35,630	)