Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 29, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net income	$ 45,010	$ 37,092
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of property, equipment and leasehold improvements	4,762	4,509
Amortization of premiums and accretion of discounts on short-term investments	0	7
Deferred rent	(314)	(330)
Provision for contract losses and doubtful accounts	1,657	1,688
Stock-based compensation	12,728	10,659
Deferred income tax provision	(421)	(1,284)
Changes in operating assets and liabilities:
Accounts receivable	(39,051)	(7,403)
Prepaid expenses and other assets	1,049	(342)
Accounts payable and accrued liabilities	3,950	(1,059)
Accrued payroll and employee benefits	(2,558)	(4,091)
Deferred revenues	152	(2,212)
Net cash provided by operating activities	26,964	37,234
Cash flows from investing activities:
Capital expenditures	(3,354)	(13,063)
Purchase of short-term investments	(20,997)	(36,000)
Maturity of short-term investments	4,000	29,950
Net cash used in investing activities	(20,351)	(19,113)
Cash flows from financing activities:
Payroll taxes for restricted stock units	(9,520)	(7,685)
Repurchase of common stock	(8,431)	(24,456)
Exercise of share-based payment awards	1,733	1,499
Dividends and dividend equivalents rights	(16,419)	(14,174)
Net cash used in financing activities	(32,637)	(44,816)
Effect of foreign currency exchange rates on cash and cash equivalents	866	(631)
Net decrease in cash and cash equivalents	(25,158)	(27,326)
Cash and cash equivalents at beginning of period	114,967	125,751
Cash and cash equivalents at end of period	$ 89,809	$ 98,425