Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities:
Net loss	$ (7,409)	$ (8,165)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	3,569	4,138
Stock-based compensation	3,653	5,636
Change in deferred taxes	59	32
Non-recurring gain	0	(1,107)
Loss on sale of property and equipment	49	0
Decrease in:
Accounts receivable, net	16,439	23,808
Prepaid expenses and other assets	982	228
Increase (decrease) in:
Accounts payable	3,483	555
Accrued payroll and related liabilities	14	(1,016)
Other accrued liabilities	(956)	(1,548)
Deferred revenue	(10,281)	(8,134)
Other long-term liabilities	(85)	138
Net cash provided by operating activities	9,517	14,565
Cash flows from investing activities:
Payments for purchase of property and equipment	(1,214)	(2,436)
Purchases of marketable securities	(15,224)	(33,368)
Sales of marketable securities	1,001	4,600
Maturities of marketable securities	16,053	23,051
Net cash provided by (used in) investing activities	616	(8,153)
Cash flows from financing activities:
Proceeds from exercise of stock options	39	627
Taxes paid related to net share settlement of equity awards	(144)	(167)
Repayments of term loans	(600)	(600)
Non-recurring gain	0	1,107
Net cash provided by (used in) financing activities	(705)	967
Net increase in cash and cash equivalents	9,428	7,379
Effect of exchange rate changes	(47)	51
Cash and cash equivalents, beginning of period	9,870	20,594
Cash and cash equivalents, end of period	$ 19,251	$ 28,024