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Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Balance Sheet Components (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash and cash equivalents
Cash	$ 9,706us-gaap_Cash	$ 8,598us-gaap_Cash
Cash equivalents:
Money market funds	94,037us-gaap_MoneyMarketFundsAtCarryingValue	104,021us-gaap_MoneyMarketFundsAtCarryingValue
Certificates of deposit	25	25
Total cash equivalents	94,062us-gaap_CashEquivalentsAtCarryingValue	104,046us-gaap_CashEquivalentsAtCarryingValue
Cash and cash equivalents	103,768	112,644	119,572	112,644	128,299
Accounts Receivable
Accounts receivable	40,670us-gaap_AccountsReceivableGross	38,260us-gaap_AccountsReceivableGross
Allowance for doubtful accounts	(481)	(393)
Accounts receivable, net	40,189us-gaap_AccountsReceivableNet	37,867us-gaap_AccountsReceivableNet
Property and equipment, net
Total property and equipment	32,695us-gaap_PropertyPlantAndEquipmentGross	29,740us-gaap_PropertyPlantAndEquipmentGross
Less accumulated depreciation	(15,023)	(12,908)
Property and equipment, net	17,672us-gaap_PropertyPlantAndEquipmentNet	16,832us-gaap_PropertyPlantAndEquipmentNet
Computer equipment
Property and equipment, net
Total property and equipment	20,201	18,384
Software
Property and equipment, net
Total property and equipment	2,526	2,417
Office furniture
Property and equipment, net
Total property and equipment	2,313	2,071
Leasehold improvements
Property and equipment, net
Total property and equipment	5,326	5,123
Construction in progress
Property and equipment, net
Total property and equipment	$ 2,329	$ 1,745