Significant Accounting Policies - Summary of Post-Trade Services Revenue by Timing of Recognition (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Significant Accounting Policies [Line Items]
Revenues	$ 186,057	$ 195,464
Post-trade Services [Member]
Significant Accounting Policies [Line Items]
Revenues	9,912	10,261
Post-trade Services [Member] | Transferred over Time [Member]
Significant Accounting Policies [Line Items]
Revenues	9,871	10,020
Post-trade Services [Member] | Transferred at a Point in Time [Member]
Significant Accounting Policies [Line Items]
Revenues	$ 41	$ 241