Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2018	Mar. 31, 2017
Cash flows from operating activities:
Net income	$ 20,340	$ 16,576
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization of property, equipment and leasehold improvements	1,555	1,566
Deferred rent	(74)	(129)
Provision for contract losses and doubtful accounts	561	458
Stock-based compensation	6,289	5,655
Deferred income tax provision	(815)	426
Changes in operating assets and liabilities:
Accounts receivable	(7,700)	(9,395)
Prepaid expenses and other assets	(5,520)	(2,974)
Accounts payable and accrued liabilities	1,829	3
Accrued payroll and employee benefits	(12,383)	(12,491)
Deferred revenues	(390)	(1,479)
Net cash provided by (used in) operating activities	3,692	(1,784)
Cash flows from investing activities:
Capital expenditures	(6,810)	(1,307)
Purchase of short-term investments	(11,934)	(9,000)
Maturity of short-term investments	8,000	0
Net cash used in investing activities	(10,744)	(10,307)
Cash flows from financing activities:
Payroll taxes for restricted stock units	(8,637)	(9,517)
Repurchase of common stock	0	(1,304)
Exercise of share-based payment awards	310	287
Dividends and dividend equivalents rights	(6,959)	(5,374)
Net cash used in financing activities	(15,286)	(15,908)
Effect of foreign currency exchange rates on cash and cash equivalents	696	118
Net decrease in cash and cash equivalents	(21,642)	(27,881)
Cash and cash equivalents at beginning of period	124,794	114,967
Cash and cash equivalents at end of period	$ 103,152	$ 87,086