Note 7 - Net (Loss) Income Per Common Share - Reconciliation of Net Income (Loss) Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Net (loss) income attributable to Earthstone Energy, Inc.		$ (5,445)	$ 11,770	$ (5,076)	$ 3,343
Net (loss) income per common share attributable to Earthstone Energy, Inc.:
Basic (in dollars per share)		$ (0.18)	$ 0.41	$ (0.17)	$ 0.12
Diluted (in dollars per share)		$ (0.18)	$ 0.41	$ (0.17)	$ 0.12
Weighted average common shares outstanding:
Basic (in shares)		30,073,635	29,032,842	29,810,705	28,883,907
Add potentially dilutive securities:
Unvested restricted stock units (1) (in shares)	[1]	0	0	0	0
Unvested performance units (1) (in shares)	[1]	0	0	0	0
Diluted weighted average common shares outstanding (in shares)		30,073,635	29,032,842	29,810,705	28,883,907

[1] For the three and nine months ended September 30, 2020 and 2019, the Company had no dilutive effect related to unvested restricted stock units or performance units as, under the treasury stock method, the proceeds from the average unrecognized expense for both during these periods were in excess of the weighted average outstanding fair value for the unvested shares for the same periods.