Supplemental Oil and Gas Information (Unaudited) - Additional Information (Detail) - MMBoe	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Extractive Industries [Abstract]
Percent of discount factor to proved reserves	10.00%
Increase (reduction) in reserves	(49.2)	(22.8)
Downward price revisions in proved reserve	50.1	25.9
Upward revision due to lower maintenance cost	10.7
Extensions and discoveries	0.46
Downward revisions due to updated well performance data		12.1
Acquisition of oil and gas properties		69.7

Acquisition of oil and gas properties.

No definition available.

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- Definition

Discounted future net cash flows relating to proved oil and gas reserves ten percent annual discount for estimated timing of cash flows discount factor.

+ References

No definition available.

+ Details

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- Definition

Proved developed and undeveloped reserve downward recovery energy.

+ References

No definition available.

+ Details

Name:	ampy_ProvedDevelopedAndUndevelopedReserveDownwardRecoveryEnergy
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- Definition

Proved developed and undeveloped reserves downward revision due to updated well performance data.

+ References

No definition available.

+ Details

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- Definition

Proved developed and undeveloped reserves upward revision due to lower maintenance cost.

+ References

No definition available.

+ Details

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- References

No definition available.

+ Details

Name:	srt_ExtractiveIndustriesAbstract
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- Definition

Energy measure of increase in quantity of proved reserve of oil and gas resulting from the extension of the proved acreage of previously discovered reservoir or discovery of new field with proved reserve or of new reservoir of proved reserve in old field, stated in a unit of energy. For example, but not limited to, barrel of oil equivalents (BOE) or one thousand cubic feet of natural gas equivalent (Mcfe).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher SEC
-Name Form 20-F
-Section Item 18
-Subsection Instruction 2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 5
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61831-109447

+ Details

Name:	srt_ProvedDevelopedAndUndevelopedReserveExtensionAndDiscoveryEnergy
Namespace Prefix:	srt_
Data Type:	num:energyItemType
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- Definition

Energy measure of increase (decrease) of quantity of proved reserve of oil and gas, stated in a unit of energy. For example, but not limited to, barrel of oil equivalents (BOE) or one thousand cubic feet of natural gas equivalent (Mcfe).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher SEC
-Name Form 20-F
-Section Item 18
-Subsection Instruction 2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61831-109447

+ Details

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