Quarterly report pursuant to Section 13 or 15(d)

Basis of Presentation of Interim Period Statements - Additional Information (Detail)

v3.8.0.1
Basis of Presentation of Interim Period Statements - Additional Information (Detail)
9 Months Ended
Sep. 30, 2017
USD ($)
Company
Sep. 30, 2016
USD ($)
Dec. 31, 2016
USD ($)
Organization Consolidation And Presentation Of Financial Statements [Abstract]      
Revenue recognition professional employer services contracts term 1 year    
Professional employer service contract cancellation and termination period 30 days    
Number of wholly-owned insurance companies | Company 2    
Cash and cash equivalents, maturity term 3 months    
Trading securities $ 0   $ 0
Allowance for doubtful accounts 265,000   78,000
Estimate of liability for unpaid safety incentives 27,600,000   24,800,000
Income taxes paid (received) 2,500,000 $ (1,100,000)  
Deferred income taxes     $ 25,200,000
Restricted cash and investments $ 70,400,000