Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Long-term Purchase Commitment [Line Items]

Summary of Changes in Asset Retirement Obligations

The following table summarizes the changes in this liability from December 31, 2014 through December 31, 2017 (in thousands):

Balance, December 31, 2014	$	41,954
Accretion	4,748
Payments made	(511		)
Revaluation	(26,000		)
Currency translation adjustments	(4,245		)
Balance, December 31, 2015	15,946
Accretion	2,292
Payments made	(159		)
Currency translation adjustments	469
Balance, December 31, 2016	18,548
Accretion	2,812
Payments made	(160		)
Currency translation adjustments	1,404
Balance, December 31, 2017	$	22,604

Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]

Future minimum payments required under operating leases that have initial or remaining non-cancellable lease terms in excess of one year at December 31, 2017, are as follows (in thousands):

For year ending:
December 31, 2018	$	6,750
December 31, 2019	7,174
December 31, 2020	6,409
December 31, 2021	5,896
December 31, 2022	4,376
Thereafter	60,790
Total future minimum lease payments	$	91,395

Summary of Purchase and Sale Commitments [Table Text Block]

At December 31, 2017, such commitments included the following (in thousands):

	Volume (barrels)	Value
Fixed price purchases	1,461	$	83,545
Fixed price sales	3,148	$	178,629
Floating price purchases	10,915	$	641,934
Floating price sales	12,152	$	574,335

Long-term Purchase Commitment [Table Text Block]

Our Crude Supply and Logistics segment has minimum volume commitments for pipeline transportation of crude oil. At December 31, 2017, the approximate amount of future obligations is as follows (in thousands):

For year ending:
December 31, 2018	$	21,631
December 31, 2019	21,877
December 31, 2020	20,585
December 31, 2021	12,976
December 31, 2022	13,231
Thereafter	20,312
Total expected future payments	$	110,612

Our SemGas segment has a take or pay contractual obligation related to the fractionation of natural gas liquids through June 2023. At December 31, 2017, the approximate amount of future obligations is as follows (in thousands):

For year ending:
December 31, 2018	$	10,552
December 31, 2019	9,567
December 31, 2020	8,864
December 31, 2021	7,175
December 31, 2022	6,753
Thereafter	2,791
Total expected future payments	$	45,702