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Notice required to cancel purchase agreements, days

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Number of Sites Requiring Additional Investigation

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Number of Sites With Limited Soil and Groundwater Impact

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Number of Sites in Various Stages of Follow-up

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Site contingency number of sites checked.

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Undiscounted Expected Future Asset Retirement Obligation Cost

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Unrecorded Unconditional Purchase Obligation, Minimum Volume Per Day

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Unrecorded unconditional purchase obligation, annual amount

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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.

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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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-Section S99
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-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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Amount of increase (decrease) in the asset retirement obligation from changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation.

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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)(4)
-URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849

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Amount of rent expense incurred for leased assets, including but not limited to, furniture and equipment, that is not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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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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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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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.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 440
-SubTopic 10
-Section 50
-Paragraph 4
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-URI http://asc.fasb.org/extlink&oid=73718637&loc=d3e25336-109308

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Commitments and Contingencies (Details Textual)	1 Months Ended	12 Months Ended
Commitments and Contingencies (Details Textual)	Oct. 31, 2015	Dec. 31, 2016 USD ($) Number_Of_Sites bbl	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Commitments and Contingencies (Textual) [Abstract]
Estimated cost to retire facilities		$ 122,000,000
Asset Retirement Obligation, Revision of Estimate			$ (26,000,000)
Operating leases, rent expense		$ 15,000,000	$ 15,500,000	$ 16,200,000
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
White Cliffs Pipeline Transportation Capacity [Member] \| White Cliffs Pipeline, LLC [Member]
Oil and Gas Delivery Commitments and Contracts [Line Items]
Unrecorded Unconditional Purchase Obligation, Minimum Volume Per Day \| bbl		5,000
Unrecorded Unconditional Purchase Obligation, Term	5 years
Commitments and Contingencies (Textual) [Abstract]
Unrecorded unconditional purchase obligation, annual amount		$ 9,400,000
Third-party pipeline [Member]
Oil and Gas Delivery Commitments and Contracts [Line Items]
Unrecorded Unconditional Purchase Obligation, Minimum Volume Per Day \| bbl		5,000
Unrecorded Unconditional Purchase Obligation, Term		7 years
Commitments and Contingencies (Textual) [Abstract]
Unrecorded unconditional purchase obligation, annual amount		$ 11,900,000
Capital Addition Purchase Commitments [Member] \| Maurepas Pipeline, LLC [Member]
Commitments and Contingencies (Textual) [Abstract]
Purchase Obligation, Due in Next Twelve Months		$ 180,000,000
Kansas sites [Member]
Commitments and Contingencies (Textual) [Abstract]
Site contingency number of sites checked \| Number_Of_Sites		6
Sites completing assessment \| Number_Of_Sites		4
Number of Sites With Limited Soil and Groundwater Impact \| Number_Of_Sites		2
Number of Sites Requiring Additional Investigation \| Number_Of_Sites		2
Kansas sites [Member] \| Crude Transportation [Member]
Commitments and Contingencies (Textual) [Abstract]
Site contingency number of sites checked \| Number_Of_Sites		5
Kansas sites [Member] \| SemGas [Member]
Commitments and Contingencies (Textual) [Abstract]
Site contingency number of sites checked \| Number_Of_Sites		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