Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 28, 2018	Sep. 29, 2017
Cash flows from operating activities:
Net income	$ 56,218	$ 45,010
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of property, equipment and leasehold improvements	4,710	4,762
Amortization of premiums and accretion of discounts on short-term investments	(51)	0
Deferred rent	(87)	(314)
Provision for contract losses and doubtful accounts	1,359	1,657
Stock-based compensation	13,605	12,728
Deferred income tax provision	(2,510)	(421)
Changes in operating assets and liabilities:
Accounts receivable	(14,170)	(39,051)
Prepaid expenses and other assets	(8,999)	1,049
Accounts payable and accrued liabilities	(3,609)	3,950
Accrued payroll and employee benefits	(202)	(2,558)
Deferred revenues	562	152
Net cash provided by operating activities	46,826	26,964
Cash flows from investing activities:
Capital expenditures	(12,170)	(3,354)
Purchase of short-term investments	(37,788)	(20,997)
Maturity of short-term investments	28,000	4,000
Net cash used in investing activities	(21,958)	(20,351)
Cash flows from financing activities:
Payroll taxes for restricted stock units	(8,839)	(9,520)
Repurchase of common stock	0	(8,431)
Exercise of share-based payment awards	1,065	1,733
Dividends and dividend equivalents rights	(20,497)	(16,419)
Net cash used in financing activities	(28,271)	(32,637)
Effect of foreign currency exchange rates on cash and cash equivalents	(414)	866
Net decrease in cash and cash equivalents	(3,817)	(25,158)
Cash and cash equivalents at beginning of period	124,794	114,967
Cash and cash equivalents at end of period	$ 120,977	$ 89,809