Long-Term Incentive Plans - Summary of Fair Value Assumptions (Detail) - PSUs [Member] - $ / shares		9 Months Ended
Jan. 01, 2020	Sep. 30, 2020
Share Price Target 12.50 [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share price targets		$ 12.50
Risk-free interest rate	1.61%
Dividend yield	12.10%
Expected volatility	60.00%
Calculated fair value per PSU	$ 3.66
Share Price Target 15.00 [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share price targets		15.00
Risk-free interest rate	1.61%
Dividend yield	12.10%
Expected volatility	60.00%
Calculated fair value per PSU	$ 2.98
Share Price Target 17.50 [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share price targets		$ 17.50
Risk-free interest rate	1.61%
Dividend yield	12.10%
Expected volatility	60.00%
Calculated fair value per PSU	$ 2.46

Share-based compensation arrangement by share-based payment award, fair value assumptions, share price targets.

No definition available.

Name:	ampy_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsSharePriceTargets
Namespace Prefix:	ampy_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(iii)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

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

- Definition

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(ii)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

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

- Definition

The risk-free interest rate assumption that is used in valuing an option on its own shares.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(iv)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

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

- 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

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

- Definition

Price of a single share of a number of saleable stocks of a company.

+ References

No definition available.

+ Details

Name:	us-gaap_SharePrice
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_AwardTypeAxis=ampy_RestrictedStockUnitsWithMarketAndServiceVestingConditionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=ampy_SharePriceTargetOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=ampy_SharePriceTargetTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MeasurementInputTypeAxis=ampy_SharePriceTargetThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: