Long-Term Debt - Credit Facility - Additional Information (Detail) - USD ($)	9 Months Ended
Sep. 30, 2020	Nov. 01, 2020
Line Of Credit Facility [Line Items]
Borrowing base	$ 270,000,000.0
Maturity date	Nov. 02, 2023
Letters of credit outstanding	$ 0
Credit Facility [Member]
Line Of Credit Facility [Line Items]
Borrowing base		$ 260,000,000.0
Monthly reduction of line of credit facility current borrowing capacity	$ 5,000,000.0
Line of credit facility, covenant terms	0
Minimum [Member] \| Credit Facility [Member]
Line Of Credit Facility [Line Items]
Borrowing base	$ 285,000,000.0
Increase in percentage of priority lien assets	85.00%
Line of credit facility decrease limit of cash and cash equivalents	$ 30,000,000.0
Line of credit facility increase limit of transaction-related expense add-backs	$ 5,000,000.0
HedgingLiabilitiesNoncurrent	30.00%
Maximum [Member] \| Credit Facility [Member]
Line Of Credit Facility [Line Items]
Borrowing base	$ 450,000,000.0
Increase in percentage of priority lien assets	90.00%
Line of credit facility decrease limit of cash and cash equivalents	$ 25,000,000.0
Line of credit facility increase limit of transaction-related expense add-backs	$ 20,000,000.0
HedgingLiabilitiesNoncurrent	60.00%

Increase in percentage of priority lien assets.

No definition available.

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

- Definition

Line of credit facility decrease limit of cash and cash equivalents.

+ References

No definition available.

+ Details

Name:	ampy_LineOfCreditFacilityDecreaseLimitOfCashAndCashEquivalents
Namespace Prefix:	ampy_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Line of credit facility increase limit of Transaction related expense add backs.

+ References

No definition available.

+ Details

Name:	ampy_LineOfCreditFacilityIncreaseLimitOfTransactionRelatedExpenseAddBacks
Namespace Prefix:	ampy_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Monthly reduction of line of credit facility current borrowing capacity.

+ References

No definition available.

+ Details

Name:	ampy_MonthlyReductionOfLineOfCreditFacilityCurrentBorrowingCapacity
Namespace Prefix:	ampy_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

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

- Definition

Percentage derived by dividing the change in value of a hedging instrument by the change in the value of the hedged item.

+ References

No definition available.

+ Details

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

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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

- Definition

Description of the conditions for borrowing under the credit facility including the nature of any restrictions.

+ 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=120391452&loc=d3e13212-122682

+ Details

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

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

+ 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

- Details

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Namespace Prefix:
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Balance Type:
Period Type:

- Details

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- Details

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