Significant Accounting Policies - Summary of Information Services Revenue by Timing of Recognition (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Significant Accounting Policies [Line Items]
Revenues	$ 162,093	$ 164,006	$ 533,891	$ 517,779
Information Services [Member]
Significant Accounting Policies [Line Items]
Revenues	9,608	8,501	28,614	25,570
Information Services [Member] | Transferred over Time [Member]
Significant Accounting Policies [Line Items]
Revenues	9,389	8,227	27,946	23,852
Information Services [Member] | Transferred at a Point in Time [Member]
Significant Accounting Policies [Line Items]
Revenues	$ 219	$ 274	$ 668	$ 1,718