The adjustment to reduce the value of existing agreements that specify the lessee's rights to use the leased property. This expense is charged when the estimates of future profits generated by the leased property are reduced.

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Leases - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2022	Dec. 31, 2020
Leasehold Improvements [Member] \| California [Member]
Lessee Lease Description [Line Items]
Right-of-use asset impairments		$ 3.7
Leasehold impairments		$ 1.3
Office Space [Member]
Lessee Lease Description [Line Items]
Variable incentive payment received	$ 3.5
Topic 842 [Member] \| SiriusDecisions, Inc [Member] \| Facility Lease [Member]
Lessee Lease Description [Line Items]
Right-of-use asset impairments			$ 2.3
Leasehold impairments			$ 1.1