CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Cash flows from operating activities:
Net income	$ 13,884	$ 8,786
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	4,212	3,948
Amortization of marketable securities	657	507
Stock-based compensation	2,155	1,790
Deferred income taxes	5,341	2,012
Changes in operating assets and liabilities,net of effects from acquisitions:
Restricted cash	(331)	397
Accounts receivable	(5,028)	(13,955)
Prepaid insurance	(3,362)	593
Other current assets	(41)	(3,415)
Other assets	(3,570)	(1,965)
Accounts payable	(1,648)	(681)
Payroll taxes and other payroll deductions payable	9,339	6,467
Accrued worksite employee payroll expense	14,523	56,563
Accrued health insurance costs	(227)	1,871
Accrued workers' compensation costs	547	2,329
Accrued corporate payroll, commissions and otheraccrued liabilities	(5,362)	(8,646)
Income taxes payable/receivable	2,167	2,487
Total adjustments	19,372	50,302
Net cash provided by operating activities	33,256	59,088
Cash flows from investing activities:
Marketable securities purchases	(1,443)	(5,154)
Marketable securities proceeds from dispositions	0	1,365
Marketable securities proceeds from maturities	850	4,402
Cash exchanged for acquisitions	(1,200)	(10,800)
Property and equipment	(3,435)	(3,326)
Net cash used in investing activities	(5,228)	(13,513)
Cash flows from financing activities:
Purchase of treasury stock	(3,253)	(3,089)
Dividends paid	(3,899)	(3,971)
Proceeds from the exercise of stock options	803	2,534
Income tax benefit from stock-based compensation	1,401	1,711
Other	260	216
Net cash used in financing activities	(4,688)	(2,599)
Net increase in cash and cash equivalents	23,340	42,976
Cash and cash equivalents at beginning of period	211,208	234,829
Cash and cash equivalents at end of period	$ 234,548	$ 277,805