Significant Accounting Policies - Summary of Information Services Revenue by Timing of Recognition (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Significant Accounting Policies [Line Items]
Revenues	$ 511,352	$ 435,565	$ 393,422
Information Services [Member]
Significant Accounting Policies [Line Items]
Revenues	30,730	28,227	25,806
Information Services [Member] \| Transferred over Time [Member]
Significant Accounting Policies [Line Items]
Revenues	29,619	27,475	25,242
Information Services [Member] \| Transferred at a Point in Time [Member]
Significant Accounting Policies [Line Items]
Revenues	$ 1,111	$ 752	$ 564

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

Name:	us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration