Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 29, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net income	$ 38,765	$ 30,367
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of property, equipment and leasehold improvements	3,149	3,195
Amortization of premiums and accretion of discounts on short-term investments	(19)	0
Deferred rent	(153)	(205)
Provision for contract losses and doubtful accounts	782	805
Stock-based compensation	10,033	9,187
Deferred income tax provision	(1,379)	1,217
Changes in operating assets and liabilities:
Accounts receivable	(7,214)	(20,840)
Prepaid expenses and other assets	(4,553)	3,365
Accounts payable and accrued liabilities	(3,018)	928
Accrued payroll and employee benefits	(8,182)	(9,806)
Deferred revenues	(295)	(1,022)
Net cash provided by operating activities	27,916	17,191
Cash flows from investing activities:
Capital expenditures	(8,949)	(2,526)
Purchase of short-term investments	(19,939)	(13,000)
Maturity of short-term investments	16,000	0
Net cash used in investing activities	(12,888)	(15,526)
Cash flows from financing activities:
Payroll taxes for restricted stock units	(8,637)	(9,520)
Repurchase of common stock	0	(7,004)
Exercise of share-based payment awards	692	638
Dividends and dividend equivalents rights	(13,732)	(10,995)
Net cash used in financing activities	(21,677)	(26,881)
Effect of foreign currency exchange rates on cash and cash equivalents	(372)	482
Net decrease in cash and cash equivalents	(7,021)	(24,734)
Cash and cash equivalents at beginning of period	124,794	114,967
Cash and cash equivalents at end of period	$ 117,773	$ 90,233