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Equity Plans - Schedule of Activity under Equity Incentive Plans (Detail) - 2007 and 2016 Equity Incentive Plans [Member] - USD ($) $ / shares in Units, $ in Thousands | 12 Months Ended
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Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Options Available for Grant, Beginning balance | 147,219 | 116,832 | 70,082 |
Options Available for Grant, Additional options authorized | 1,697,088 | 431,411 | 240,425 |
Options Available for Grant, Options granted | (1,679,979) | (408,623) | (199,519) |
Options Available for Grant, Options exercised | 0 | 0 | 0 |
Options Available for Grant, Options forfeited |  | 7,599 | 5,844 |
Options Available for Grant, Ending balance | 164,328 | 147,219 | 116,832 | 70,082
Number of Options Outstanding, Beginning balance | 833,178 | 476,006 | 284,879 |
Number of Options Outstanding, Options granted | 1,679,979 | 408,623 | 199,519 |
Number of Options Outstanding, Options exercised | (119,328) | (43,852) | (2,548) |
Number of Options Outstanding, Options forfeited |  | (7,599) | (5,844) |
Number of Options Outstanding, Ending balance | 2,393,829 | 833,178 | 476,006 | 284,879
Weighted-Average Exercise Price Per Share, Beginning balance | $ 1.33 | $ 1.40 | $ 1.10 |
Number of Options Outstanding, Options exercisable | 492,714 |  |  |
Weighted-Average Exercise Price Per Share, Options granted | $ 14.24 | 1.24 | 1.83 |
Number of Options Outstanding, Options vested and expected to vest | 2,369,135 |  |  |
Weighted-Average Exercise Price Per Share, Options exercised | $ 1.28 | 1.30 | 1.30 |
Weighted-Average Exercise Price Per Share, Options forfeited |  | 1.40 | 1.13 |
Weighted-Average Exercise Price Per Share, Ending balance | 10.39 | $ 1.33 | $ 1.40 | $ 1.10
Weighted-Average Exercise Price Per Share, Options exercisable | 5.19 |  |  |
Weighted-Average Exercise Price Per Share, Options vested and expected to vest | $ 10.37 |  |  |
Weighted-Average Remaining Contractual Life (years) | 8 years 9 months 15 days | 8 years 6 months 22 days | 8 years 15 days | 7 years 11 months 1 day
Weighted-Average Remaining Contractual Life (years), Options exercisable | 7 years 8 months 12 days |  |  |
Weighted-Average Remaining Contractual Life (years), Options vested and expected to vest | 8 years 9 months 15 days |  |  |
Aggregate Intrinsic Value, Options Outstanding | $ 27,820 |  |  |
Aggregate Intrinsic Value, Options exercisable | 8,286 |  |  |
Aggregate Intrinsic Value, Options vested and expected to vest | $ 27,596 |  |  |

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- Definition Share based compensation arrangement by share based payment award number of shares available for grant granted in period. + References No definition available. + Details
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- Definition Number of additional shares authorized for issuance under an established share-based compensation plan. + References No definition available. + Details
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- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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