CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash flows from operating activities:
Net income	$ 30,470	$ 22,440	$ 16,574
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	15,218	14,950	16,561
Loss on exchange of assets	4,408	0	0
Amortization of marketable securities	2,172	1,650	0
Stock-based compensation	8,601	8,126	10,064
Deferred income taxes	(46)	1,179	(4,397)
Changes in operating assets and liabilities, net of acquisitions:
Restricted cash	(3,533)	(4,768)	30
Accounts receivable	(28,826)	(18,874)	2,501
Prepaid insurance	3,678	(10,494)	14,427
Other current assets	(2,862)	(2,141)	418
Other assets	(652)	4,180	698
Accounts payable	1,776	1,136	(1,150)
Payroll taxes and other payroll deductions payable	23,556	17,499	3,931
Accrued worksite employee payroll expense	20,620	16,559	(36,816)
Accrued health insurance costs	(5,992)	9,045	(8,341)
Accrued workers' compensation costs	8,791	8,748	4,446
Accrued corporate payroll, commissions and other accrued liabilities	(1,871)	9,556	(10,188)
Income taxes payable/receivable	(1,597)	49	(7,927)
Total adjustments	43,441	56,400	(15,743)
Net cash provided by operating activities	73,911	78,840	831
Marketable securities:
Purchases	(51,397)	(60,003)	(6,039)
Proceeds from maturities	31,706	18,301	225
Proceeds from dispositions	3,907	2,748	0
Investments and acquisitions, net of cash acquired	(14,555)	(12,918)	(720)
Property and equipment:
Purchases	(31,440)	(6,764)	(8,019)
Proceeds from dispositions	82	54	36
Net cash used in investing activities	(61,697)	(58,582)	(14,517)
Cash flows from financing activities:
Purchase of treasury stock	(25,079)	(7,852)	(2,024)
Dividends paid	(15,742)	(13,527)	(13,272)
Proceeds from the exercise of stock options	3,956	7,183	2,838
Principal repayments on capital lease obligations	0	0	(537)
Income tax benefit from stock-based compensation	2,166	860	706
Other	(1,136)	822	870
Net cash used in financing activities	(35,835)	(12,514)	(11,419)
Net increase (decrease) in cash and cash equivalents	(23,621)	7,744	(25,105)
Cash and cash equivalents at beginning of year	234,829	227,085	252,190
Cash and cash equivalents at end of year	211,208	234,829	227,085
Supplemental disclosures:
Cash paid for income taxes	$ 19,782	$ 13,492	$ 23,694