The amount of capital expenditure limitation under the debt agreement.

No definition available.

Name:	snde_DebtInstrumentCovenantCapitalExpenditureLimitation
Namespace Prefix:	snde_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of general and administrative expense limitation under the debt agreement.

+ References

No definition available.

+ Details

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Namespace Prefix:	snde_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The percentage of excess cash flow used to pay down the balance on Revolving Facility.

+ References

No definition available.

+ Details

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Namespace Prefix:	snde_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Increase in basis points on interest rate margin.

+ References

No definition available.

+ Details

Name:	snde_IncreaseInBasisPointsOnInterestRateMargin
Namespace Prefix:	snde_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of interest payable-in-kind.

+ References

No definition available.

+ Details

Name:	snde_PercentageOfInterestPayableInKind
Namespace Prefix:	snde_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=snde_TermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
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Balance Type:
Period Type:

SUBSEQUENT EVENTS (Details) $ in Millions		3 Months Ended
SUBSEQUENT EVENTS (Details) $ in Millions	Jun. 24, 2020 USD ($)	Mar. 31, 2020 USD ($)	Jan. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Apr. 23, 2018 USD ($)
Subsequent Event [Line Items]
Maximum borrowing capacity					$ 250.0
Revolving Facility
Subsequent Event [Line Items]
Maximum borrowing capacity		$ 190.0	$ 500.0	$ 250.0
Term Loan
Subsequent Event [Line Items]
Debt instrument, variable rate		8.00%
Subsequent event
Subsequent Event [Line Items]
Percentage of excess cash flow used to pay down Revolving Facility	50.00%
Capital expenditure limitation for the period from May 1, 2020 to September 30, 2020	$ 5.0
General and administrative expense limitation per quarter for the second and third quarters of 2020	$ 3.0
Basis points on interest rate margin	25
Subsequent event \| Revolving Facility
Subsequent Event [Line Items]
Maximum borrowing capacity	$ 170.0
Subsequent event \| Term Loan
Subsequent Event [Line Items]
Debt instrument, variable rate	10.00%
Interest payable-in-kind	2.00%