CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Cash flows from operating activities:
Net income	$ 13,173	$ 13,884
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	5,135	4,212
Amortization of marketable securities	441	657
Stock-based compensation	2,310	2,155
Deferred income taxes	3,252	5,341
Changes in operating assets and liabilities:
Restricted cash	(225)	(331)
Accounts receivable	(10,814)	(5,028)
Prepaid insurance	(1,267)	(3,362)
Other current assets	(4,108)	(41)
Other assets	(3,109)	(3,570)
Accounts payable	(1,458)	(1,648)
Payroll taxes and other payroll deductions payable	4,977	9,339
Accrued worksite employee payroll expense	18,645	14,523
Accrued health insurance costs	(6,458)	(227)
Accrued workers' compensation costs	418	547
Accrued corporate payroll, commissions and other accrued liabilities	(3,978)	(5,362)
Income taxes payable/receivable	538	2,167
Total adjustments	4,299	19,372
Net cash provided by operating activities	17,472	33,256
Marketable securities:
Purchases	(40,046)	(1,443)
Proceeds from dispositions	4,138	0
Proceeds from maturities	1,001	850
Investments and acquisitions	0	(1,200)
Property and equipment	(2,843)	(3,435)
Net cash used in investing activities	(37,750)	(5,228)
Cash flows from financing activities:
Purchase of treasury stock	(13,498)	(3,253)
Dividends paid	(4,349)	(3,899)
Proceeds from the exercise of stock options	118	803
Income tax benefit from stock-based compensation	665	1,401
Other	230	260
Net cash used in financing activities	(16,834)	(4,688)
Net increase (decrease) in cash and cash equivalents	(37,112)	23,340
Cash and cash equivalents at beginning of year	264,544	211,208
Cash and cash equivalents at end of year	$ 227,432	$ 234,548