Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities:
Net loss	$ (3,583)	$ (2,549)
Reconciliations of net loss to net cash provided by operating activities:
Depreciation and amortization	584	460
Losses recognized on marketable securities	1	0
Gain recognized on sale and leaseback	0	(30)
Deferred income taxes	(409)	(4)
Share-based compensation	331	183
Excess tax benefit from share-based compensation	(15)	(280)
Changes in certain assets and liabilities:
Trade accounts receivable, net	(10,370)	(6,371)
Income taxes receivable	(1,596)	(7,179)
Prepaid expenses and other	(1,595)	818
Accounts payable	(870)	487
Accrued payroll, payroll taxes and related benefits	19,484	19,925
Other accrued liabilities	98	162
Income taxes payable	(1,221)	0
Workers' compensation claims liabilities	7,691	6,648
Safety incentives liability	(894)	446
Customer deposits, long-term liabilities and other assets, net	74	240
Net cash provided by operating activities	7,710	12,956
Cash flows from investing activities:
Purchase of property and equipment	(1,814)	(1,199)
Proceeds from sales and maturities of marketable securities	2,934	7,651
Purchase of marketable securities	(14,936)	(11,269)
Proceeds from maturities of restricted marketable securities	1,010	673
Purchase of restricted marketable securities	(20,938)	(1,530)
Net cash used in investing activities	(33,744)	(5,674)
Cash flows from financing activities:
Proceeds from credit-line borrowings	0	78,057
Payments on credit-line borrowings	0	(82,589)
Payments on long-term debt	(55)	(54)
Dividends paid	(1,291)	(912)
Proceeds from exercise of stock options and vesting of restricted stock units	76	204
Excess tax benefits from share-based compensation	15	280
Net cash used in financing activities	(1,255)	(5,014)
Net (decrease) increase in cash and cash equivalents	(27,289)	2,268
Cash and cash equivalents, beginning of period	93,557	45,747
Cash and cash equivalents, end of period	$ 66,268	$ 48,015