Basis of Presentation of Interim Period Statements - Additional Information (Detail) shares in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($) Company shares	Jun. 30, 2016 USD ($)	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	73,000		78,000
Estimate of liability for unpaid safety incentives	26,100,000		24,800,000
Income taxes paid (received)	$ 2,400,000	$ (1,200,000)
Anti-dilutive common shares excluded from calculation of diluted loss per share | shares	294,169
Deferred income taxes			$ 25,200,000
Restricted cash and investments	$ 93,200,000