Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2018

Accounting Policies [Abstract]

Summary of Commission Revenue by Fee Type

The following table presents commission revenue by fee type for the three months ended March 31, 2018 and 2017:

	Three Months Ended March 31,
	2018		2017
	(In thousands)
Commission revenue by fee type
Variable transaction fees
Disclosed trading	$	66,253	$	65,903
Open Trading™ - matched principal trading		13,524		11,945
Total variable transaction fees		79,777		77,848
Distribution fees and unused minimum fees		22,995		16,174
Total commissions	$	102,772	$	94,022

Summary of Information Services Revenue by Timing of Recognition

The following table presents information services revenue by timing of recognition for the three months ended March 31, 2018 and 2017:

	Three Months Ended March 31,
	2018		2017
	(In thousands)
Information services revenue by timing of recognition
Services transferred over time	$	6,842	$	5,957
Services transferred at a point in time		224		228
Total information services revenues	$	7,066	$	6,185

Summary of Post-Trade Services Revenue by Timing of Recognition

The following table presents post-trade services revenue by timing of recognition for the three months ended March 31, 2018 and 2017:

	Three Months Ended March 31,
	2018		2017
	(In thousands)
Post-trade services revenue by timing of recognition
Services transferred over time	$	4,287	$	2,450
Services transferred at a point in time		289		6
Total post-trade services revenues	$	4,576	$	2,456

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, 2017		Payments received in advance of services to be performed		Revenue recognized for services performed during the period			March 31, 2018
	(In thousands)
Information services	$	1,763	$	1,912	$	(1,652	)	$	2,023
Post-trade services		897		3,652		(3,018	)		1,531
Total deferred revenue	$	2,660	$	5,564	$	(4,670	)	$	3,554