Quarterly report pursuant to Section 13 or 15(d)

Investments in Marketable Securities - Schedule of Amortized Cost and Fair Value of Marketable Securities, Available-for-Sale, by Type of Security (Detail)

v3.2.0.727
Investments in Marketable Securities - Schedule of Amortized Cost and Fair Value of Marketable Securities, Available-for-Sale, by Type of Security (Detail) - USD ($)
$ in Thousands
Jun. 30, 2015
Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost $ 103,334 $ 14,712
Fair Value 102,864 14,752
Short-term investments [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 51,071  
Gross Unrealized Gains 4  
Gross Unrealized Losses (5)  
Fair Value 51,070  
Short-term investments [Member] | U.S. Treasuries [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 31,946  
Gross Unrealized Gains 2  
Gross Unrealized Losses (4)  
Fair Value 31,944  
Short-term investments [Member] | U.S. Government Sponsored Entities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 19,125  
Gross Unrealized Gains 2  
Gross Unrealized Losses (1)  
Fair Value 19,126  
Long-term marketable securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 52,263 14,712
Gross Unrealized Gains 30 59
Gross Unrealized Losses (499) (19)
Fair Value 51,794 14,752
Long-term marketable securities [Member] | U.S. Treasuries [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 12,597 2,974
Gross Unrealized Gains 7 7
Gross Unrealized Losses (108)  
Fair Value 12,496 2,981
Long-term marketable securities [Member] | U.S. Government Sponsored Entities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 11,837 2,019
Gross Unrealized Gains 2  
Gross Unrealized Losses (38) (3)
Fair Value 11,801 2,016
Long-term marketable securities [Member] | Corporate debt securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 17,229 7,442
Gross Unrealized Gains 12 48
Gross Unrealized Losses (295) (12)
Fair Value 16,946 7,478
Long-term marketable securities [Member] | Asset-backed securities and other [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 10,600 2,277
Gross Unrealized Gains 9 4
Gross Unrealized Losses (58) (4)
Fair Value $ 10,551 $ 2,277