v2.4.0.6

Fair value measurement (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2012
Fair value measurement |
Schedule of financial assets and financial liabilities that are measured at fair value on a recurring basis |
At December 31, 2012 |  | Level 1 |  | Level 2 |  | Total |
--- | --- | --- | --- | --- | --- | --- | ---
Assets: |  |  |  |  |  |  |  |  |  |
Cash equivalents |  | $ | 39,001 |  | $ | 2,460 |  | $ | 41,461 |
Marketable securities |  |  | — |  |  | 41,558 |  |  | 41,558 |
Restricted cash |  |  | 30 |  |  | — |  |  | 30 |
Total assets |  | $ | 39,031 |  | $ | 44,018 |  | $ | 83,049 |
At December 31, 2011 |  | Level 1 |  | Level 2 |  | Total |
--- | --- | --- | --- | --- | --- | --- | ---
Assets: |  |  |  |  |  |  |  |  |  |
Cash equivalents |  | $ | 81,082 |  | $ | — |  | $ | 81,082 |
Restricted cash |  |  | 465 |  |  | — |  |  | 465 |
Total assets |  | $ | 81,547 |  | $ | — |  | $ | 81,547 |
Schedule of reconciliation between the beginning and ending balances of preferred stock warrants that used significant unobservable inputs |
Balance at December 31, 2010 |  | $ | 140 |
Increase in the fair value of the liability |  |  | 132 |
Exercise and conversion of preferred stock warrants into common stock |  |  | (272 | )
Balance at December 31, 2011 |  | $ | — |

X
- Details
Name: | us-gaap_FairValueDisclosuresAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the fair value measurement of liabilities using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets), and gains or losses recognized in other comprehensive income (loss) and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issues, and settlements (each type disclosed separately); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs) by class of liability. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19279-110258 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 32 -Subparagraph c -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
Name: | us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of assets and liabilities, including [financial] instruments measured at fair value that are classified in stockholders' equity, if any, that are measured at fair value on a recurring basis. The disclosures contemplated herein include the fair value measurements at the reporting date by the level within the fair value hierarchy in which the fair value measurements in their entirety fall, segregating fair value measurements using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19190-110258 + Details
Name: | us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration