INCOME TAXES (Narrative) (Details) - USD ($) $ in Thousands	11 Months Ended	12 Months Ended
Dec. 31, 2018	Dec. 31, 2019
Income Tax Contingency [Line Items]
Change in valuation allowance	$ 3,135	$ 136,568
Percent of tax benefit under tax receivable agreement	85.00%	85.00%
Benefit retained of the remaining cash savings (percent)		15.00%
Alta Mesa Contributor \| Common Class A
Income Tax Contingency [Line Items]
Conversion of common shares (in shares)	2,752,312	2,181,600

Number of shares issued during the period as a result of the conversion of convertible securities.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration