Quarterly report pursuant to Section 13 or 15(d)

Workers' Compensation Claims - Summarizes Aggregate Workers' Compensation Reserve Activity (Detail)

v3.8.0.1
Workers' Compensation Claims - Summarizes Aggregate Workers' Compensation Reserve Activity (Detail) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Workers Compensation Reserve [Abstract]        
Workers’ compensation claims liabilities, Beginning balance $ 330,079 $ 277,050 $ 312,537 $ 255,675
Add: claims expense accrual        
Current period 39,316 38,094 112,469 103,875
Prior periods (280) (999) 4,984 (1,547)
Total expense accrual 39,036 37,095 117,453 102,328
Less: claim payments related to        
Current period 6,082 5,596 11,362 10,565
Prior periods 18,466 16,618 67,928 55,507
Total paid 24,548 22,214 79,290 66,072
Add: Change in claims incurred in excess of retention limits 118   (6,015)  
Workers’ compensation claims liabilities, Ending balance 344,685 291,931 344,685 291,931
Incurred but not reported (IBNR) $ 177,166 $ 145,722 $ 177,166 $ 145,722