Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Operating Activities:
Net loss	$ (10,154)	$ (10,858)
Adjustments to reconcile net loss to net cash and cash equivalents provided by (used in) operating activities
Depreciation and amortization	2,201	1,747
Stock-based compensation	6,231	5,142
Provision for deferred income taxes	3	26
Amortization of bond premium discount	221	2
Noncash rent expense	1,112	168
Unrealized currency translation	(252)	(448)
Changes in assets and liabilities, net of acquisitions
Accounts receivable	347	(1,451)
Prepaid expenses and other assets	(2,403)	(1,151)
Deferred commission expense	(299)	4
Accounts payable	(804)	(1,110)
Accrued expenses	(1,154)	652
Deferred rent	(23)
Deferred revenue	8,152	6,462
Net cash and cash equivalents provided by (used in) operating activities	3,178	(815)
Investing Activities:
Purchases of investments	(8,969)	(25,784)
Maturities of investments	8,875
Purchases of property and equipment	(6,641)	(1,025)
Capitalization of software development costs	(1,434)	(770)
Acquisition of a business		(600)
Net cash and cash equivalents used in investing activities	(8,169)	(28,179)
Financing Activities:
Secondary offering proceeds, net of offering costs paid of $138		34,114
Employee taxes paid related to the net share settlement of stock-based awards	(958)
Proceeds related to the issuance of common stock under stock plans	2,992	966
Repayments of capital lease obligations	(142)	(24)
Net cash and cash equivalents provided by financing activities	1,892	35,056
Effect of exchange rate changes on cash and cash equivalents	538	(408)
Net (decrease) increase in cash and cash equivalents	(2,561)	5,654
Cash and cash equivalents, beginning of period	55,580	123,721
Cash and cash equivalents, end of period	53,019	129,375
Supplemental cash flow disclosure:
Cash and cash equivalents paid for interest	87	29
Cash and cash equivalents paid for income taxes	73
Non-cash investing and financing activities:
Property acquired under capital lease	257
Offering costs incurred but not yet paid		295
Capital expenditures incurred but not yet paid	$ 2,974	$ 5