Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
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- Definition

Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 20
-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 16
-Article 9

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the required periodic payments applied to principal.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

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- Details

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- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SecuredDebtMember
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- Details

Name:	us-gaap_DebtInstrumentAxis=dk_LionTermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
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- Details

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- Details

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- Details

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Long-Term Obligations and Notes Payable Lion Term Loan Narrative (Details) - USD ($) $ in Millions	May. 14, 2015	Dec. 31, 2015	May. 13, 2015
Debt Instrument [Line Items]
Debt and capital lease obligations		$ 981.1
Term loan facility [Member]
Debt Instrument [Line Items]
Debt and capital lease obligations		261.3
Term loan facility [Member] \| Secured Debt [Member] \| Lion Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	$ 6.9
London Interbank Offered Rate (LIBOR) [Member] \| Term loan facility [Member] \| Secured Debt [Member] \| Lion Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Description of Variable Rate Basis	LIBOR
Reference Rate [Member] \| Term loan facility [Member] \| Secured Debt [Member] \| Lion Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Description of Variable Rate Basis	base rate
Debt Instrument, Basis Spread on Variable Rate	5.50%
Debt and capital lease obligations		$ 261.3
Debt, Weighted Average Interest Rate		5.50%
Interest Rate Floor [Member] \| Term loan facility [Member] \| Secured Debt [Member] \| Lion Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Description of Variable Rate Basis	interest rate floor
Fifth Third Bank [Member] \| Term loan facility [Member] \| Secured Debt [Member] \| Lion Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 275.0		$ 99.0