Business Realignment Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2018
Business realignment expenses rollforward
Liability balance, beginning	$ 77	$ 821
Business Realignment Expenses	5	405
Cash Payments	(82)	(980)
Liability balance, ending	0	$ 77
Accounting Standards Update		Accounting Standards Update 2016-02 [Member]	Accounting Standards Update 2016-09 [Member]
Cumulative Effect, Period of Adoption, Adjustment
Business realignment expenses rollforward
Liability balance, beginning		$ (169)
Employee severance and benefit costs
Business realignment expenses rollforward
Liability balance, beginning	77	652
Business Realignment Expenses	5	405
Cash Payments	(82)	(980)
Liability balance, ending	0	77
Employee severance and benefit costs | Cumulative Effect, Period of Adoption, Adjustment
Business realignment expenses rollforward
Liability balance, beginning		0
Occupancy and other costs
Business realignment expenses rollforward
Liability balance, beginning	0	169
Business Realignment Expenses	0	0
Cash Payments	0	0
Liability balance, ending	0	0
Occupancy and other costs | Cumulative Effect, Period of Adoption, Adjustment
Business realignment expenses rollforward
Liability balance, beginning		(169)
GovDeals | Employee severance and benefit costs
Business realignment expenses rollforward
Liability balance, beginning	4	0
Business Realignment Expenses	0	29
Cash Payments	(4)	(25)
Liability balance, ending	0	4
GovDeals | Employee severance and benefit costs | Cumulative Effect, Period of Adoption, Adjustment
Business realignment expenses rollforward
Liability balance, beginning		0
RSCG | Employee severance and benefit costs
Business realignment expenses rollforward
Liability balance, beginning	20	0
Business Realignment Expenses	0	84
Cash Payments	(20)	(64)
Liability balance, ending	0	20
RSCG | Employee severance and benefit costs | Cumulative Effect, Period of Adoption, Adjustment
Business realignment expenses rollforward
Liability balance, beginning		0
CAG | Employee severance and benefit costs
Business realignment expenses rollforward
Liability balance, beginning	53	414
Business Realignment Expenses	5	120
Cash Payments	(58)	(481)
Liability balance, ending	0	53
CAG | Employee severance and benefit costs | Cumulative Effect, Period of Adoption, Adjustment
Business realignment expenses rollforward
Liability balance, beginning		0
CAG | Occupancy and other costs
Business realignment expenses rollforward
Liability balance, beginning	0	169
Business Realignment Expenses	0	0
Cash Payments	0	0
Liability balance, ending	0	0
CAG | Occupancy and other costs | Cumulative Effect, Period of Adoption, Adjustment
Business realignment expenses rollforward
Liability balance, beginning		(169)
Corporate & Other | Employee severance and benefit costs
Business realignment expenses rollforward
Liability balance, beginning	0	238
Business Realignment Expenses	0	172
Cash Payments	0	(410)
Liability balance, ending	0	0
Corporate & Other | Employee severance and benefit costs | Cumulative Effect, Period of Adoption, Adjustment
Business realignment expenses rollforward
Liability balance, beginning		0
Corporate & Other | Occupancy and other costs
Business realignment expenses rollforward
Liability balance, beginning	0	0
Business Realignment Expenses	0	0
Cash Payments	0	0
Liability balance, ending	$ 0	0
Corporate & Other | Occupancy and other costs | Cumulative Effect, Period of Adoption, Adjustment
Business realignment expenses rollforward
Liability balance, beginning		$ 0