Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2021

Accounting Policies [Abstract]

Summary of Commission Revenue by Fee Type

The following table presents commission revenue by fee type:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2021		2020		2021		2020
	(In thousands)
Commission revenue by fee type
Variable transaction fees
Disclosed trading	$	75,044	$	80,354	$	258,443	$	260,233
Open Trading - matched principal trading		34,356		40,565		120,557		128,296
U.S. Treasuries - matched principal trading		2,748		2,264		8,645		9,851
Total variable transaction fees		112,148		123,183		387,645		398,380
Distribution fees and unused minimum fees		30,678		27,403		87,450		80,252
Total commissions	$	142,826	$	150,586	$	475,095	$	478,632

Summary of Information Services Revenue by Timing of Recognition

The following table presents information services revenue by timing of recognition:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2021		2020		2021		2020
	(In thousands)
Information services revenue by timing of recognition
Services transferred over time	$	9,389	$	8,227	$	27,946	$	23,852
Services transferred at a point in time		219		274		668		1,718
Total information services revenues	$	9,608	$	8,501	$	28,614	$	25,570

Summary of Post-Trade Services Revenue by Timing of Recognition

The following table presents post-trade services revenue by timing of recognition:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2021		2020		2021		2020
	(In thousands)
Post-trade services revenue by timing of recognition
Services transferred over time	$	9,444	$	4,557	$	29,544	$	12,655
Services transferred at a point in time		—		132		9		241
Total post-trade services revenues	$	9,444	$	4,689	$	29,553	$	12,896

Summary of Revenue Recognized from Contract Liabilities and Remaining Balance

The revenue recognized from contract liabilities and the remaining balance is shown below:

	December 31, 2020		Payments received in advance of services to be performed		Revenue recognized for services performed during the period			Foreign Currency Translation			September 30, 2021
	(In thousands)
Information services	$	3,203	$	8,064	$	(7,614	)	$	—		$	3,653
Post-trade services		1,045		11,810		(11,740	)		(15	)		1,100
Total deferred revenue	$	4,248	$	19,874	$	(19,354	)	$	(15	)	$	4,753