Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jul. 01, 2016
Cash flows from operating activities:
Net income	$ 30,367	$ 25,803
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of property, equipment and leasehold improvements	3,195	2,927
Amortization of premiums and accretion of discounts on short-term investments	0	14
Deferred rent	(205)	(184)
Provision for contract losses and doubtful accounts	805	1,131
Stock-based compensation	9,187	7,929
Deferred income tax provision	1,217	424
Changes in operating assets and liabilities:
Accounts receivable	(20,840)	(4,863)
Prepaid expenses and other assets	3,365	(5,198)
Accounts payable and accrued liabilities	928	(1,716)
Accrued payroll and employee benefits	(9,806)	(9,712)
Deferred revenues	(1,022)	(2,010)
Net cash provided by operating activities	17,191	14,545
Cash flows from investing activities:
Capital expenditures	(2,526)	(3,382)
Purchase of short-term investments	(13,000)	(24,000)
Maturity of short-term investments	0	21,450
Net cash used in investing activities	(15,526)	(5,932)
Cash flows from financing activities:
Payroll taxes for restricted stock units	(9,520)	(7,613)
Repurchase of common stock	(7,004)	(4,458)
Exercise of share-based payment awards	638	1,229
Dividends and dividend equivalents rights	(10,995)	(9,515)
Net cash used in financing activities	(26,881)	(20,357)
Effect of foreign currency exchange rates on cash and cash equivalents	482	(464)
Net decrease in cash and cash equivalents	(24,734)	(12,208)
Cash and cash equivalents at beginning of period	114,967	125,751
Cash and cash equivalents at end of period	$ 90,233	$ 113,543