Business Combinations - Summary of Estimated Fair Values and Useful Lives of Identifiable Intangible Assets (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2015
Oct. 31, 2015
Developed Technology [Member]    
Finite-Lived Intangible Assets [Line Items]    
Preliminary estimated useful life 5 years 10 months 24 days  
Customer Relationships [Member]    
Finite-Lived Intangible Assets [Line Items]    
Preliminary estimated useful life 6 years 8 months 12 days  
Non-compete Agreements [Member]    
Finite-Lived Intangible Assets [Line Items]    
Preliminary estimated useful life 4 years 9 months 18 days  
Logentries [Member]    
Finite-Lived Intangible Assets [Line Items]    
Identifiable intangible assets $ 9,425 $ 9,425
Logentries [Member] | Developed Technology [Member]    
Finite-Lived Intangible Assets [Line Items]    
Identifiable intangible assets $ 8,300  
Preliminary estimated useful life 6 years  
Logentries [Member] | Customer Relationships [Member]    
Finite-Lived Intangible Assets [Line Items]    
Identifiable intangible assets $ 900  
Preliminary estimated useful life 7 years  
Logentries [Member] | Trade Name [Member]    
Finite-Lived Intangible Assets [Line Items]    
Identifiable intangible assets $ 225  
Preliminary estimated useful life 1 year  
NT OBJECTives, Inc. [Member]    
Finite-Lived Intangible Assets [Line Items]    
Identifiable intangible assets $ 2,090  
NT OBJECTives, Inc. [Member] | Developed Technology [Member]    
Finite-Lived Intangible Assets [Line Items]    
Identifiable intangible assets $ 1,950  
Preliminary estimated useful life 6 years  
NT OBJECTives, Inc. [Member] | Customer Relationships [Member]    
Finite-Lived Intangible Assets [Line Items]    
Identifiable intangible assets $ 100  
Preliminary estimated useful life 4 years  
NT OBJECTives, Inc. [Member] | Non-compete Agreements [Member]    
Finite-Lived Intangible Assets [Line Items]    
Identifiable intangible assets $ 40  
Preliminary estimated useful life 2 years