Business Combinations - Additional Information (Detail) shares in Millions	6 Months Ended
	Jun. 30, 2020 USD ($) Client_List shares	Jun. 30, 2019 USD ($) Business Client_List shares	Dec. 31, 2019 USD ($)
Business Acquisition, Contingent Consideration [Line Items]
Consideration paid in cash	$ 9,400,000
Consideration paid in common stock	900,000
Contingent consideration	4,800,000
Contingent consideration arrangements - High	6,200,000
Aggregate fair value of contingent consideration	4,700,000
Contingent consideration, current	15,646,000		$ 16,193,000
Contingent consideration, non-current	11,815,000		$ 15,896,000
Annual revenue	6,100,000
Number of businesses acquired | Business		1
Business combination contingent consideration liability other adjustments based on projected future results of acquisition	(200,000)	$ (200,000)
Consideration paid in cash	$ 5,900,000	$ 11,300,000
Number of common stock issued | shares	0.1	0.1
Contingent Purchase Price Liability – Current [Member]
Business Acquisition, Contingent Consideration [Line Items]
Contingent consideration, current	$ 2,000,000.0
Contingent Purchase Price Liability – Non-current [Member]
Business Acquisition, Contingent Consideration [Line Items]
Contingent consideration, non-current	$ 2,700,000
Alliance Insurance Services, Inc. [Member]
Business Acquisition, Contingent Consideration [Line Items]
Effective date of acquisition	Feb. 01, 2020
Acquired entity, name	Alliance Insurance Services, Inc.
Pension Dynamics Company, LLC [Member]
Business Acquisition, Contingent Consideration [Line Items]
Effective date of acquisition	Feb. 01, 2020
Acquired entity, name	Pension Dynamics Company, LLC
Sunshine Systems [Member]
Business Acquisition, Contingent Consideration [Line Items]
Effective date of acquisition	Feb. 01, 2020
Acquired entity, name	Sunshine Systems
Wenner Group, LLC [Member]
Business Acquisition, Contingent Consideration [Line Items]
Effective date of acquisition		Jan. 01, 2019
Acquired entity, name		Wenner Group, LLC
Consideration paid in cash		$ 1,300,000
Contingent consideration		1,800,000
Contingent consideration arrangements - High		1,800,000
Annual revenue		2,400,000
Wenner Group, LLC [Member] | Contingent Purchase Price Liability – Current [Member]
Business Acquisition, Contingent Consideration [Line Items]
Contingent consideration, current		600,000
Wenner Group, LLC [Member] | Contingent Purchase Price Liability – Non-current [Member]
Business Acquisition, Contingent Consideration [Line Items]
Contingent consideration, non-current		1,200,000
Series of Business Acquisition [Member]
Business Acquisition, Contingent Consideration [Line Items]
Goodwill	$ 11,200,000	$ 2,200,000
Acquisition of Client Lists [Member]
Business Acquisition, Contingent Consideration [Line Items]
Consideration paid in cash	600,000
Contingent consideration	$ 300,000
Number of client list purchased | Client_List		0
Acquisition of Client Lists [Member] | Benefits and Insurance Services Practice Group [Member]
Business Acquisition, Contingent Consideration [Line Items]
Number of client list purchased | Client_List	2
Acquisition of Client Lists [Member] | Financial Service Practice Group [Member]
Business Acquisition, Contingent Consideration [Line Items]
Number of client list purchased | Client_List	1
Previous Client List Purchases [Member]
Business Acquisition, Contingent Consideration [Line Items]
Consideration paid in cash	$ 300,000	$ 300,000