Equity (Deficit) - Summary of Changes in Number of Outstanding Common Units and Shares of Common Stock (Detail) - shares	1 Months Ended	2 Months Ended	6 Months Ended	9 Months Ended
	Aug. 05, 2019	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2019
Equity [Abstract]
Balance	22,305,256	22,334,010	22,181,881	22,181,881
Issuance of common stock			0
Ratio to convert Amplify shares		0.933
Common stock issued to Legacy Amplify stockholders		20,837,633		20,837,633
Midstates stock outstanding and acquired with Merger		20,415,005
Treasury shares acquired from the Merger		205,861
Restricted stock units vested	38,181	602,053	412,938
Repurchase of common shares	(9,427)	(11,740)	(120,163)
Common stock repurchased and retired under share repurchase program		(1,723,146)	(169,400)
Cancelation and retirement of shares		(347,567)
Balance	22,334,010	39,978,099	22,305,256	39,978,099