Organization, Basis of Presentation and Summary of Significant Accounting Policies - Condonsed Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue, current portion	$ 35,209		$ 28,345
Deferred revenue, noncurrent portion	23,964		29,244
Accumulated deficit	(514,549)		$ (495,479)
Topic 606 [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue, current portion		$ 29,626
Deferred revenue, noncurrent portion		26,846
Accumulated deficit		(494,362)
Adjustments [Member] \| Topic 606 [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue, current portion	(4,664)	1,281
Deferred revenue, noncurrent portion	1,801	(2,398)
Accumulated deficit	(2,863)	1,117
Balances without adoption of Topic 606 [Member] \| Topic 606 [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue, current portion	39,873	28,345
Deferred revenue, noncurrent portion	22,163	29,244
Accumulated deficit	$ (517,412)	$ (495,479)

The carrying amount of consideration received or receivable as of the balance sheet date on potential earnings that were not recognized as revenue in conformity with GAAP, and which are expected to be recognized as such within one year or the normal operating cycle, if longer, including sales, license fees, and royalties, but excluding interest income.

The noncurrent portion of deferred revenue amount as of balance sheet date. Deferred revenue is a liability related to a revenue producing activity for which revenue has not yet been recognized, and is not expected to be recognized in the next twelve months. Generally, an entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

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