Restricted Investments - Additional Information (Detail) - USD ($) $ in Millions	Jun. 24, 2019	Nov. 20, 2018	Oct. 05, 2018
Investments Debt And Equity Securities [Abstract]
Proceeds from Beta Decommissioning Trust account	$ 90.0	$ 1.0	$ 61.5

The cash inflow from a decommissioning trust fund.

No definition available.

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