Summary of Significant Accounting Policies - Earnings (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Accounting Policies [Abstract]
Net (loss) income from continuing operations	$ (455)	$ (6,467)	$ 19,735	$ (14,006)
Less: net income (loss) attributable to non-controlling interest, continuing operations		1,146	(1,554)	913
Numerator for basic EPS - Net (loss) income from continuing operations attributable to Great Elm Group, Inc.	455	(7,613)	21,289	(14,919)
Net income from discontinued operations	12,203	332	13,202	3,818
Less: net (loss) income attributable to non-controlling interest, discontinued operations		(1,372)	1,504	(754)
Numerator for basic EPS - Net (loss) income from discontinued operations, attributable to Great Elm Group, Inc.	12,203	1,704	11,698	4,572
Effect of dilutive securities:
Interest expense associated with Convertible Notes, continuing operations			1,451
Numerator for diluted EPS - Net (loss) income from continuing operations attributable to Great Elm Group, Inc., after the effect of dilutive securities	(455)	(7,613)	22,740	(14,919)
Numerator for diluted EPS - Net (loss) income from discontinued operations, attributable to Great Elm Group, Inc.	$ 12,203	$ 1,704	$ 11,698	$ 4,572
Denominator:
Denominator for basic EPS - Weighted average shares of common stock outstanding	28,997	26,842	28,779	26,963
Effect of dilutive securities:
Restricted stock			1,328
Convertible Notes			10,566
Denominator for diluted EPS - Weighted average shares of common stock outstanding after the effect of dilutive securities	28,997	26,842	40,673	26,963
Basic income (loss) per share from:
Continuing operations	$ (0.02)	$ (0.28)	$ 0.74	$ (0.55)
Discontinued operations	0.42	0.06	0.41	0.17
Basic net income (loss) per share	0.40	(0.22)	1.15	(0.38)
Diluted income (loss) per share from:
Continuing operations	(0.02)	(0.28)	0.56	(0.55)
Discontinued operations	0.42	0.06	0.29	0.17
Diluted net income (loss) per share	$ 0.40	$ (0.22)	$ 0.85	$ (0.38)