Composition of Certain Financial Statement Captions - Property and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Sep. 30, 2024
Property, Plant and Equipment [Line Items]
Less: accumulated depreciation and amortization	$ (45,572)	$ (77,453)
Total	67,713	38,465
Data processing equipment and purchased software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	42,121	74,084
Internal-use software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	47,151	16,510
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	8,113	9,473
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 15,900	$ 15,851