Related Party Transactions - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended		15 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2018
Sales Effected To Related Party [Member] | Maximum [Member]
Related Party Transaction [Line Items]
Accounts receivable, related parties, current	$ 100,000		$ 100,000
Stockholder One [Member] | Fourth Amended And Restated Management Services Termination Agreement [Member]
Related Party Transaction [Line Items]
Payment to related parties pursuant to agreement			4,500,000
Stockholder One [Member] | Annual Cash Compensation Agreement With The Stockholder For Additional Management Services [Member]
Related Party Transaction [Line Items]
Payment to related parties pursuant to agreement					$ 1,200,000
Payable to related party pursuant to an agreement							$ 950,000
Goldman Sachs And Stockholder One [Member] | Fourth Amended And Restated Management Services Termination Agreement [Member]
Related Party Transaction [Line Items]
Prepaid expenses related party current	0		0			$ 300,000
Goldman Sachs And Affiliates [Member]
Related Party Transaction [Line Items]
Accounts receivable, related parties, current	400,000		400,000			1,400,000
Goldman Sachs And Affiliates [Member] | Sales Effected To Related Party [Member]
Related Party Transaction [Line Items]
Revenue from related parties	1,300,000	$ 600,000	4,800,000	$ 700,000
Stockholder One And Affiliates [Member] | Maximum [Member]
Related Party Transaction [Line Items]
Accounts receivable, related parties, current						$ 100,000
Stockholder One And Affiliates [Member] | Sales Effected To Related Party [Member]
Related Party Transaction [Line Items]
Revenue from related parties	$ 100,000	$ 100,000	300,000	$ 100,000
Goldman Sachs [Member] | Fourth Amended And Restated Management Services Termination Agreement [Member]
Related Party Transaction [Line Items]
Payment to related parties pursuant to agreement			$ 3,200,000