CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net income	$ 39,390	$ 28,004	$ 32,032
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	18,565	21,387	21,064
Impairment charges and other	10,480	3,687	6,021
Amortization of marketable securities	836	1,891	2,119
Stock-based compensation	13,345	11,053	11,103
Deferred income taxes	(14,733)	(1,733)	(2,288)
Changes in operating assets and liabilities:
Restricted cash	6,622	7,888	(4,779)
Accounts receivable	(25,549)	34,893	(19,623)
Prepaid insurance	13,884	(10,663)	4,982
Other current assets	514	(5,596)	(2,402)
Other assets	(22,069)	(32,013)	(18,091)
Accounts payable	707	1,996	(982)
Payroll taxes and other payroll deductions payable	29,052	10,737	(12,930)
Accrued worksite employee payroll expense	(30,479)	18,595	23,731
Accrued health insurance costs	(4,686)	13,226	(8,839)
Accrued workers’ compensation costs	26,159	15,805	7,815
Accrued corporate payroll, commissions and other accrued liabilities	4,105	18,517	556
Income taxes payable/receivable	(1,060)	4,039	(4,825)
Total adjustments	25,693	113,709	2,632
Net cash provided by operating activities	65,083	141,713	34,664
Marketable securities:
Purchases	(10,558)	(69,578)	(54,756)
Proceeds from maturities	10,593	28,494	15,201
Proceeds from dispositions	17,869	56,880	8,026
Property and equipment:
Purchases	(17,844)	(19,124)	(11,562)
Proceeds from sale of aircraft	12,159	0	0
Proceeds from dispositions	153	122	57
Net cash provided by (used in) investing activities	12,372	(3,206)	(43,034)
Cash flows from financing activities:
Purchase of treasury stock	(67,113)	(20,769)	(17,229)
Dividends paid	(21,153)	(69,493)	(17,386)
Proceeds from the exercise of stock options	374	279	1,448
Income tax benefit from stock-based compensation	2,216	889	1,621
Other	1,303	1,288	1,127
Net cash used in financing activities	(84,373)	(87,806)	(30,419)
Net increase (decrease) in cash and cash equivalents	(6,918)	50,701	(38,789)
Cash and cash equivalents at beginning of year	276,456	225,755	264,544
Cash and cash equivalents at end of year	269,538	276,456	225,755
Supplemental disclosures:
Cash paid for income taxes, net	$ 39,806	$ 16,429	$ 27,191