Business Combinations - Intangible Assets Acquired (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Customer relationships
Acquired Indefinite-lived Intangible Assets [Line Items]
Amortization Period	4 years 9 months 18 days	4 years 9 months 18 days
A2iA
Acquired Indefinite-lived Intangible Assets [Line Items]
Amount assigned			$ 28,610
A2iA | Completed technologies
Acquired Indefinite-lived Intangible Assets [Line Items]
Amortization Period			7 years
Amount assigned			$ 13,015
A2iA | Customer relationships
Acquired Indefinite-lived Intangible Assets [Line Items]
Amortization Period			5 years
Amount assigned			$ 15,360
A2iA | Trade names
Acquired Indefinite-lived Intangible Assets [Line Items]
Amortization Period			5 years
Amount assigned			$ 235
ICAR
Acquired Indefinite-lived Intangible Assets [Line Items]
Amount assigned			$ 6,407
ICAR | Completed technologies
Acquired Indefinite-lived Intangible Assets [Line Items]
Amortization Period			5 years
Amount assigned			$ 4,956
ICAR | Customer relationships
Acquired Indefinite-lived Intangible Assets [Line Items]
Amortization Period			2 years
Amount assigned			$ 1,298
ICAR | Trade names
Acquired Indefinite-lived Intangible Assets [Line Items]
Amortization Period			3 years
Amount assigned			$ 153