Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities
Net income	$ 4,796	$ 1,396
Reconciliation of net income to net cash provided by operating activities
Deferred income taxes	1,236	(439)
Share-based earn-out liability		(72)
Depreciation and amortization of property and equipment	3,431	3,259
Amortization of intangible assets	2,332	2,359
Provision for doubtful accounts	873	592
Stock-based compensation	4,486	3,992
Other, net	9
Changes in assets and liabilities
Accounts receivable	(1,607)	(2,495)
Deferred costs	(3,025)	(2,592)
Other current and non-current assets	(3)	(3,138)
Accounts payable	195	719
Accrued compensation	(546)	439
Accrued expenses	206	464
Deferred revenue	5,772	4,325
Deferred rent	(249)	(17)
Net cash provided by operating activities	17,906	8,792
Cash flows from investing activities
Purchases of property and equipment	(3,334)	(3,070)
Purchases of marketable securities	(22,350)	(8,499)
Maturities of marketable securities	21,000	2,500
Acquisitions of businesses and intangible assets, net of cash acquired	(500)	(18,062)
Net cash used in investing activities	(5,184)	(27,131)
Cash flows from financing activities
Net proceeds from exercise of options to purchase common stock	1,244	1,749
Excess tax benefits from exercise of options to purchase common stock		1,421
Net proceeds from employee stock purchase plan	1,011	786
Net cash provided by financing activities	2,255	3,956
Effect of foreign currency exchange rate changes	890	5
Net increase (decrease) in cash and cash equivalents	15,867	(14,378)
Cash and cash equivalents at beginning of period	115,877	121,538
Cash and cash equivalents at end of period	$ 131,744	$ 107,160