Summary of Significant Accounting Policies - Earnings (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2024	Dec. 31, 2023
Accounting Policies [Abstract]
Net (loss) income from continuing operations	$ 1,354	$ (239)	$ 4,328	$ 2,519
Less: net income attributable to non-controlling interest, continuing operations	178	111	513	111
Numerator for basic EPS - Net (loss) income from continuing operations attributable to Great Elm Group, Inc.	1,176	(350)	3,815	2,408
Net income from discontinued operations	0	0	0	16
Numerator for basic EPS - Net income (loss) from discontinued operations, attributable to Great Elm Group, Inc.	0	0	0	16
Effect of dilutive securities:
Interest expense associated with Convertible Notes, continuing operations	0	0	939	0
Numerator for diluted EPS - Net (loss) income from continuing operations attributable to Great Elm Group, Inc., after the effect of dilutive securities	1,176	(350)	4,754	2,408
Numerator for diluted EPS - Net income (loss) from discontinued operations, attributable to Great Elm Group, Inc.	$ 0	$ 0	$ 0	$ 16
Denominator:
Denominator for basic EPS - Weighted average shares of common stock outstanding	27,983	29,889	28,531	29,734
Effect of dilutive securities:
Restricted stock	784	0	784	1,182
Convertible Notes	0	0	10,478	0
Denominator for diluted EPS - Weighted average shares of common stock outstanding after the effect of dilutive securities	28,767	29,889	39,793	30,916
Net income attributable to shareholders per share
Basic net income per share	$ 0.04	$ (0.01)	$ 0.13	$ 0.08
Diluted net income per share	$ 0.04	$ (0.01)	$ 0.12	$ 0.08