Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 28, 2019	Jun. 29, 2018
Cash flows from operating activities:
Net income	$ 43,706	$ 38,765
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of property, equipment and leasehold improvements	3,232	3,149
Amortization of premiums and accretion of discounts on short-term investments	(298)	(19)
Deferred rent		(153)
Provision for contract losses and doubtful accounts	1,786	782
Stock-based compensation	9,741	10,033
Deferred income tax provision	(141)	(1,379)
Changes in operating assets and liabilities:
Accounts receivable	(25,707)	(7,214)
Prepaid expenses and other current assets	(1,760)	(4,553)
Change in operating leases	(209)
Accounts payable and accrued liabilities	6,846	(3,018)
Accrued payroll and employee benefits	(11,761)	(8,182)
Deferred revenues	(616)	(295)
Net cash provided by operating activities	24,819	27,916
Cash flows from investing activities:
Capital expenditures	(12,494)	(8,949)
Purchase of short-term investments	(38,693)	(19,939)
Maturity of short-term investments	31,000	16,000
Net cash used in investing activities	(20,187)	(12,888)
Cash flows from financing activities:
Payroll taxes for restricted stock units	(11,183)	(8,637)
Exercise of stock-based payment awards	845	692
Dividends and dividend equivalents rights	(16,899)	(13,732)
Net cash used in financing activities	(27,237)	(21,677)
Effect of foreign currency exchange rates on cash and cash equivalents	(2)	(372)
Net decrease in cash and cash equivalents	(22,607)	(7,021)
Cash and cash equivalents at beginning of period	127,059	124,794
Cash and cash equivalents at end of period	$ 104,452	$ 117,773