Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net loss	$ (11,227)	$ (8,003)
Reconciliations of net loss to net cash used by operating activities:
Depreciation and amortization	942	749
Gain recognized on investments		(1)
Share-based compensation	882	359
Excess tax benefit from share-based compensation		(265)
Changes in certain operating assets and liabilities:
Trade accounts receivable	(12,793)	(73,302)
Income taxes receivable	(3,078)	(2,969)
Prepaid expenses and other	(2,931)	(2,595)
Accounts payable	(1,435)	723
Accrued payroll, payroll taxes and related benefits	20,383	66,767
Other accrued liabilities	(1,151)	392
Income taxes payable	(3,041)
Workers' compensation claims liabilities	13,696	9,468
Safety incentives liability	(631)	563
Customer deposits, long-term liabilities and other assets, net	(474)	297
Net cash used by operating activities	(858)	(7,817)
Cash flows from investing activities:
Purchase of property and equipment	(902)	(1,368)
Purchase of investments	(491)	(207)
Proceeds from sales and maturities of investments	5,502	178
Purchase of restricted cash and investments	(359,331)	(26,830)
Proceeds from sales and maturities of restricted cash and investments	325,581	55,634
Net cash provided by (used in) investing activities	(29,641)	27,407
Cash flows from financing activities:
Proceeds from credit-line borrowings		11,300
Payments on credit-line borrowings		(11,300)
Payments on long-term debt	(56)	(55)
Common stock repurchased on vesting of restricted stock units	(68)	(40)
Dividends paid	(1,813)	(1,586)
Proceeds from exercise of stock options and vesting of restricted stock units	97	72
Excess tax benefits from share-based compensation		265
Net cash used in financing activities	(1,840)	(1,344)
Net increase (decrease) in cash and cash equivalents	(32,339)	18,246
Cash and cash equivalents, beginning of period	50,768	25,218
Cash and cash equivalents, end of period	$ 18,429	$ 43,464