Goodwill - Changes in Goodwill (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Jun. 30, 2024	Sep. 30, 2023
Goodwill
Balance at the beginning of the period	$ 89,388	$ 88,910
Sierra acquisition (see Note 3)	7,977
Translation adjustments	200	478
Balance at the end of the period	97,565	89,388
GovDeals Goodwil
Goodwill
Balance at the beginning of the period	53,814	53,814
Sierra acquisition (see Note 3)	7,977
Translation adjustments	0	0
Balance at the end of the period	61,791	53,814
CAG Goodwill
Goodwill
Balance at the beginning of the period	21,016	20,538
Translation adjustments	200	478
Balance at the end of the period	21,216	21,016
Machinio
Goodwill
Balance at the beginning of the period	14,558	14,558
Translation adjustments	0	0
Balance at the end of the period	$ 14,558	$ 14,558