CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities:
Net income	$ 49,991	$ 35,628
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	5,213	4,254
Amortization of marketable securities	(20)	(19)
Stock-based compensation	3,135	4,503
Deferred income taxes	7,116	3,728
Changes in operating assets and liabilities:
Accounts receivable	(2,567)	6,149
Prepaid insurance	(24,897)	(56)
Other current assets	(1,402)	(3,543)
Other assets	(8,597)	(7,641)
Accounts payable	(930)	353
Payroll taxes and other payroll deductions payable	(26,674)	2,081
Accrued worksite employee payroll expense	14,072	1,974
Accrued health insurance costs	20,720	(2,317)
Accrued workers’ compensation costs	6,094	5,555
Accrued corporate payroll, commissions and other accrued liabilities	(24,854)	(20,822)
Income taxes payable/receivable	7,129	13,617
Total adjustments	(26,422)	7,854
Net cash provided by operating activities	23,569	43,482
Marketable securities:
Purchases	(512)	(711)
Proceeds from maturities	525	704
Property and equipment:
Purchases	(6,585)	(11,567)
Net cash used in investing activities	(6,572)	(11,574)
Cash flows from financing activities:
Purchase of treasury stock	(8,565)	(9,317)
Dividends paid	(8,402)	(5,272)
Other	351	318
Net cash used in financing activities	(16,616)	(14,271)
Net increase in cash, cash equivalents and restricted cash	381	17,637
Cash, cash equivalents and restricted cash at beginning of period	395,397	328,671
Cash, cash equivalents and restricted cash at end of period	$ 395,778	$ 346,308