Marketable Securities and Cash Equivalents - Summary of Marketable Securities and Cash Equivalents (Detail) $ in Thousands	Jun. 30, 2018 USD ($)
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 43,815
Unrealized Gains	1
Unrealized Losses	(2)
Fair Value	43,814
Cash Equivalents [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	6,270
Fair Value	6,270
Cash Equivalents [Member] \| Money Market Funds [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	688
Fair Value	688
Cash Equivalents [Member] \| Commercial Paper [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	5,582
Fair Value	5,582
Marketable Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	37,545
Unrealized Gains	1
Unrealized Losses	(2)
Fair Value	37,544
Marketable Securities [Member] \| Corporate Debt Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	2,150
Unrealized Losses	(2)
Fair Value	2,148
Marketable Securities [Member] \| Commercial Paper [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	25,423
Fair Value	25,423
Marketable Securities [Member] \| Government Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	9,972
Unrealized Gains	1
Fair Value	$ 9,973

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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