Equity (Deficit) - Summary of Changes in Number of Outstanding Common Units and Shares of Common Stock (Detail) - shares		1 Months Ended	5 Months Ended	6 Months Ended	7 Months Ended	12 Months Ended
		Aug. 05, 2019	Dec. 31, 2019	Jun. 30, 2019	Aug. 05, 2019	Dec. 31, 2020	Dec. 31, 2019
Summary Of Changes In Number Of Outstanding Units Or Shares [Line Items]
Beginning balance						37,566,540
Ending balance			37,566,540			37,663,509	37,566,540
Common Stock [Member]
Summary Of Changes In Number Of Outstanding Units Or Shares [Line Items]
Beginning balance		22,305,256	22,334,010	22,181,881	22,181,881	37,566,540	22,181,881
Issuance of common stock				0		0
Restricted stock units vested		38,181	682,552	412,938		132,237
Repurchase of common shares	[1]	(9,427)	(31,697)	(120,163)		(35,268)
Common stock repurchased and retired under share repurchase program			(4,195,247)	(169,400)
Ending balance		22,334,010	37,566,540	22,305,256	22,334,010	37,663,509	37,566,540
Merger conversion ratio			0.933
Common stock issued to Legacy Amplify stockholders			20,837,633				20,837,633
Midstates stock outstanding and acquired with the Merger			20,415,005
Treasury shares acquired from the Merger			205,861
Cancelation and retirement of shares			(347,567)

[1] Represents the net settlement on vesting of restricted stock necessary to satisfy the minimum statutory tax withholding requirements.