Quarterly report pursuant to Section 13 or 15(d)

Marketable Securities and Fair Value - Summary of Company's Available-for-Sale Securities (Detail)

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Marketable Securities and Fair Value - Summary of Company's Available-for-Sale Securities (Detail) - USD ($)
$ in Thousands
Mar. 31, 2016
Dec. 31, 2015
Schedule Of Available For Sale Securities [Line Items]    
Cost Basis $ 26,754 $ 39,112
Unrealized Gain 5 1
Unrealized Loss (4) (22)
Fair Value 26,755 39,091
Money Market Funds    
Schedule Of Available For Sale Securities [Line Items]    
Cost Basis 3,543 5,421
Unrealized Gain 0 0
Unrealized Loss 0 0
Fair Value 3,543 5,421
Certificates of Deposit    
Schedule Of Available For Sale Securities [Line Items]    
Cost Basis 100 696
Unrealized Gain 0 0
Unrealized Loss 0 0
Fair Value 100 696
Corporate Debt Securities    
Schedule Of Available For Sale Securities [Line Items]    
Cost Basis 5,167 12,578
Unrealized Gain 0 1
Unrealized Loss (1) (8)
Fair Value 5,166 12,571
U.S. Government Securities    
Schedule Of Available For Sale Securities [Line Items]    
Cost Basis 17,844 21,783
Unrealized Gain 5 0
Unrealized Loss (3) (14)
Fair Value 17,846 21,769
Municipal Securities    
Schedule Of Available For Sale Securities [Line Items]    
Cost Basis   1,908
Unrealized Gain   0
Unrealized Loss   0
Fair Value   1,908
Commercial Paper    
Schedule Of Available For Sale Securities [Line Items]    
Cost Basis 11,239 6,145
Unrealized Gain 0 0
Unrealized Loss 0 0
Fair Value 11,239 6,145
Marketable Securities Including Cash Equivalents    
Schedule Of Available For Sale Securities [Line Items]    
Cost Basis 37,893 48,531
Unrealized Gain 5 1
Unrealized Loss (4) (22)
Fair Value 37,894 48,510
Less Cash Equivalents    
Schedule Of Available For Sale Securities [Line Items]    
Cost Basis 11,139 9,419
Unrealized Gain 0 0
Unrealized Loss 0 0
Fair Value $ 11,139 $ 9,419