Restatement of Previously Issued Condensed Consolidated Financial Statements - Impact on Condensed Consolidated Balance Sheet (Unaudited) (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015		Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 43,464	$ 25,218	$ 15,205	[1]	$ 11,544	[1]
Marketable securities			21,670
Trade accounts receivable, net	163,831	90,529	130,376
Income taxes receivable	4,272	1,038	14,131
Prepaid expenses and other	5,768	3,173	6,658
Restricted marketable securities and workers' compensation deposits	40,049	76,110	12,533
Deferred income taxes	20,918	20,941	18,972
Total current assets	278,302	227,009	219,545
Marketable securities			6,034
Property, equipment and software, net	23,439	22,820	22,648
Restricted certificates of deposit	10,000	0	114,335
Restricted marketable securities and workers' compensation deposits	200,447	187,916	78,516
Other assets	4,742	5,130	4,960
Goodwill	47,820	47,820	47,820
Total assets	565,645	496,777	493,858
Current liabilities:
Line of credit			5,772
Current portion of long-term debt	19,778	19,833	25,220
Accounts payable	3,940	3,217	3,500
Accrued payroll, payroll taxes and related benefits	188,110	121,343	149,999
Other accrued liabilities	6,558	6,166	6,190
Workers' compensation claims liabilities	68,115	65,581	61,830
Safety incentives liability	21,816	21,253	15,499
Total current liabilities	308,317	237,393	268,010
Long-term workers' compensation claims liabilities	197,028	190,094	169,893
Long-term debt			19,778
Deferred income taxes	13,256	13,256	8,421
Customer deposits and other long-term liabilities	1,392	1,483	1,534
Total liabilities	$ 519,993	$ 442,226	$ 467,636
Commitments and contingencies
Stockholders' equity:
Common stock, $.01 par value; 20,500 shares authorized, 7,141 shares issued and outstanding	$ 72	$ 72	$ 71
Additional paid-in capital	7,620	6,964	5,165
Accumulated other comprehensive income	3	(31)	21
Retained earnings	37,957	47,546	20,965
Total stockholders' equity	45,652	54,551	26,222	[2]	32,820	[2]
Total liabilities and stockholders' equity	$ 565,645	$ 496,777	493,858
As Previously Reported [Member]
Current assets:
Cash and cash equivalents			15,205		11,544
Marketable securities			21,670
Trade accounts receivable, net			130,376
Income taxes receivable			13,586
Prepaid expenses and other			6,658
Restricted marketable securities and workers' compensation deposits			12,533
Deferred income taxes			15,763
Total current assets			215,791
Marketable securities			6,034
Property, equipment and software, net			22,648
Restricted certificates of deposit			114,335
Restricted marketable securities and workers' compensation deposits			78,516
Other assets			4,960
Goodwill			47,820
Total assets			490,104
Current liabilities:
Line of credit			5,772
Current portion of long-term debt			25,220
Accounts payable			3,500
Accrued payroll, payroll taxes and related benefits			150,102
Other accrued liabilities			6,190
Workers' compensation claims liabilities			56,480
Safety incentives liability			15,499
Total current liabilities			262,763
Long-term workers' compensation claims liabilities			165,785
Long-term debt			19,778
Deferred income taxes			8,159
Customer deposits and other long-term liabilities			1,534
Total liabilities			$ 458,019
Commitments and contingencies
Stockholders' equity:
Common stock, $.01 par value; 20,500 shares authorized, 7,141 shares issued and outstanding			$ 71
Additional paid-in capital			5,165
Accumulated other comprehensive income			21
Retained earnings			26,828
Total stockholders' equity			32,085
Total liabilities and stockholders' equity			490,104
Restatement Adjustments [Member]
Current assets:
Cash and cash equivalents			0		$ 0
Marketable securities			0
Trade accounts receivable, net			0
Income taxes receivable			545
Prepaid expenses and other			0
Restricted marketable securities and workers' compensation deposits			0
Deferred income taxes			3,209
Total current assets			3,754
Marketable securities			0
Property, equipment and software, net			0
Restricted certificates of deposit			0
Restricted marketable securities and workers' compensation deposits			0
Other assets			0
Goodwill			0
Total assets			3,754
Current liabilities:
Line of credit			0
Current portion of long-term debt			0
Accounts payable			0
Accrued payroll, payroll taxes and related benefits			(103)
Other accrued liabilities			0
Workers' compensation claims liabilities			5,350
Safety incentives liability			0
Total current liabilities			5,247
Long-term workers' compensation claims liabilities			4,108
Long-term debt			0
Deferred income taxes			262
Customer deposits and other long-term liabilities			0
Total liabilities			$ 9,617
Commitments and contingencies
Stockholders' equity:
Common stock, $.01 par value; 20,500 shares authorized, 7,141 shares issued and outstanding			$ 0
Additional paid-in capital			0
Accumulated other comprehensive income			0
Retained earnings			(5,863)
Total stockholders' equity			(5,863)
Total liabilities and stockholders' equity			$ 3,754

[1] See Note 2. Restatement of Previously Issued Condensed Consolidated Financial Statements

[2] Restatement impacts to the Condensed Consolidated Statements of Stockholders' Equity include the first quarter of 2015 adjustment to net loss as well as previous period cumulative adjustments to beginning retained earnings. See Note 2. Restatement of Previously Issued Condensed Consolidated Financial Statements