Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Schedule of Earnings Per Share, Basic, by Common Class, Including Two Class Method [Table Text Block]

The following summarizes the calculation of basic earnings per share for the years ended December 31, 2017, 2016 and 2015 (in thousands, except per share amounts):

	Year Ended December 31, 2017
	Continuing Operations			Discontinued Operations		Net
Loss	$	(17,150	)	$	—	$	(17,150	)
less: Income attributable to noncontrolling interest	—			—		—
Loss attributable to SemGroup	$	(17,150	)	$	—	$	(17,150	)
Weighted average common stock outstanding	71,418			71,418		71,418
Basic loss per share	$	(0.24	)	$	0.00	$	(0.24	)

	Year Ended December 31, 2016
	Continuing Operations		Discontinued Operations			Net
Income	$	13,263	$	(1	)	$	13,262
less: Income attributable to noncontrolling interest	11,167		—			11,167
Income attributable to SemGroup	$	2,096	$	(1	)	$	2,095
Weighted average common stock outstanding	51,889		51,889			51,889
Basic earnings per share	$	0.04	$	0.00		$	0.04

	Year Ended December 31, 2015
	Continuing Operations		Discontinued Operations			Net
Income	$	42,816	$	(4	)	$	42,812
less: Income attributable to noncontrolling interest	12,492		—			12,492
Income attributable to SemGroup	$	30,324	$	(4	)	$	30,320
Weighted average common stock outstanding	43,787		43,787			43,787
Basic earnings per share	$	0.69	$	0.00		$	0.69

The following summarizes the calculation of diluted earnings per share for the years ended December 31, 2017, 2016 and 2015 (in thousands, except per share amounts):

	Year Ended December 31, 2017
	Continuing Operations			Discontinued Operations		Net
Loss	$	(17,150	)	$	—	$	(17,150	)
less: Income attributable to noncontrolling interest	—			—		—
Loss attributable to SemGroup	$	(17,150	)	$	—	$	(17,150	)
Weighted average common stock outstanding	71,418			71,418		71,418
Effect of dilutive securities	—			—		—
Diluted weighted average common stock outstanding	71,418			71,418		71,418
Diluted loss per share	$	(0.24	)	$	0.00	$	(0.24	)

	Year Ended December 31, 2016
	Continuing Operations		Discontinued Operations			Net
Income	$	13,263	$	(1	)	$	13,262
less: Income attributable to noncontrolling interest	11,167		—			11,167
Income attributable to SemGroup	$	2,096	$	(1	)	$	2,095
Weighted average common stock outstanding	51,889		51,889			51,889
Effect of dilutive securities	392		392			392
Diluted weighted average common stock outstanding	52,281		52,281			52,281
Diluted earnings per share	$	0.04	$	0.00		$	0.04

	Year Ended December 31, 2015
	Continuing Operations		Discontinued Operations			Net
Income	$	42,816	$	(4	)	$	42,812
less: Income attributable to noncontrolling interest	12,492		—			12,492
Income attributable to SemGroup	$	30,324	$	(4	)	$	30,320
Weighted average common stock outstanding	43,787		43,787			43,787
Effect of dilutive securities	183		183			183
Diluted weighted average common stock outstanding	43,970		43,970			43,970
Diluted earnings per share	$	0.69	$	0.00		$	0.69