Commitments and contingencies.

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- Definition

Notice required to cancel purchase agreements, days

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- Definition

Site contingency number of sites checked.

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- Definition

Sites in various stages of follow-up

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- Definition

Sites requiring additional investigation

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- Definition

Sites with limited soil and ground water impact

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- Definition

Term of unconditional purchase obligation, in years

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- Definition

Undiscounted Expected Future Asset Retirement Obligation Cost

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- Definition

Unrecorded Unconditional Purchase Obligation, Minimum Volume Per Day

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- Definition

Unrecorded unconditional purchase obligation, annual amount

+ References

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- Definition

Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.15(5))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.15(a))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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- Definition

The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Asset Retirement Obligation
-URI http://asc.fasb.org/extlink&oid=6505190

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- Definition

Minimum amount of purchase arrangement maturing in the next fiscal year following the latest fiscal year. Includes, but not limited to, recorded and unrecorded purchase obligations, long-term purchase commitments, and short-term purchase commitments.

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No definition available.

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- Definition

Minimum amount of purchase arrangement maturing in the second fiscal year following the latest fiscal year. Includes, but not limited to, recorded and unrecorded purchase obligations, long-term purchase commitments, and short-term purchase commitments.

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- Definition

The minimum number of units that must be purchased, in connection with an unconditional purchase obligation that has not been recognized for financial reporting purposes.

+ References

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- Definition

Term of the unrecognized unconditional purchase obligation, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 440
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
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Commitments and Contingencies (Details Textual)		3 Months Ended	12 Months Ended
Commitments and Contingencies (Details Textual)	Oct. 01, 2015 bbl	Mar. 31, 2017 USD ($) bbl	Dec. 31, 2016 USD ($)
Commitments and Contingencies (Textual) [Abstract]
Sites in various stages of follow-up		4
Sites with limited soil and ground water impact		2
Sites requiring additional investigation		2
Site contingency number of sites checked		6
Minimum [Member]
Commitments and Contingencies (Textual) [Abstract]
Notice required to cancel purchase agreements, days		30 days
Maximum [Member]
Commitments and Contingencies (Textual) [Abstract]
Notice required to cancel purchase agreements, days		120 days
Pipeline transportation capacity [Member]
Commitments and Contingencies (Textual) [Abstract]
Unrecorded Unconditional Purchase Obligation, Minimum Quantity Required \| bbl	5,000
Term of unconditional purchase obligation	5 years
Unrecorded unconditional purchase obligation, annual amount		$ 9,400,000
Third-party pipeline [Member]
Commitments and Contingencies (Textual) [Abstract]
Unrecorded unconditional purchase obligation, annual amount			$ 11,900,000
Unrecorded Unconditional Purchase Obligation, Minimum Volume Per Day \| bbl		5,000
Unrecorded Unconditional Purchase Obligation, Term			7 years
Capital Addition Purchase Commitments [Member] \| Maurepas Pipeline, LLC [Member]
Commitments and Contingencies (Textual) [Abstract]
Purchase Obligation, Due in Next Twelve Months			$ 180,000,000
Crude Transportation [Member]
Commitments and Contingencies (Textual) [Abstract]
Site contingency number of sites checked		5
SemCAMS [Member]
Commitments and Contingencies (Textual) [Abstract]
Asset retirement obligation liability		$ 19,300,000
Estimated cost to retire facilities		$ 123,100,000
SemGas [Member]
Commitments and Contingencies (Textual) [Abstract]
Site contingency number of sites checked		1
Proposed Department of Transportation penalty [Member]
Commitments and Contingencies (Textual) [Abstract]
Accrued Liabilities		$ 600,200
Wapiti Sour Gas Plant [Member] [Member] \| Capital Addition Purchase Commitments [Member]
Commitments and Contingencies (Textual) [Abstract]
Purchase Obligation, Due in Next Twelve Months			80,000,000
Purchase Obligation, Due in Second Year			$ 155,000,000