v3.8.0.1
Commitments and Contingencies - Rental Obligations (Detail)
$ in Millions
12 Months Ended
Dec. 31, 2017
USD ($)
renewal_term
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
May 01, 2016
USD ($)
ft²
Apr. 28, 2016
ft²
Feb. 01, 2016
ft²
Oct. 01, 2014
ft²
Operating Leases, Rent Expense $ 11.1 $ 9.0 $ 5.6        
Payments for (Proceeds from) Tenant Allowance (3.6)            
Property and Equipment, Gross 200.4 156.6          
Financing lease obligations 6.7 6.7          
Operating Leases, Future Minimum Payments, Remainder of Fiscal Year 10.1            
Operating Leases, Future Minimum Payments, 2016 11.0            
Operating Leases, Future Minimum Payments, 2017 11.4            
Operating Leases, Future Minimum Payments, 2018 11.7            
Operating Leases, Future Minimum Payments, 2019 3.7            
Thereafter 9.4            
Total $ 57.3            
Leased Buildings - 6350 Sequence [Member]              
Leased Square Footage | ft²           132,600  
Leased Buildings -6340 Sequence Drive, 6310 Sequence Drive, 6290 Sequence drive [Member]              
Leased Square Footage | ft²             219,000
Leased Buildings -232 South Dobson Road [Member]              
Leased Square Footage | ft²       78,000 148,797    
Leased Buildings -232 South Dobson Road [Member]              
Lessee Leasing Arrangements, Operating Leases, Number of Renewal Term | renewal_term 4            
Lessee, Operating Lease, Renewal Term 5 years            
Leased Buildings -6340 Sequence Drive, 6310 Sequence Drive, 6290 Sequence drive [Member]              
Lessee Leasing Arrangements, Operating Leases, Number of Renewal Term | renewal_term 2            
Lessee, Operating Lease, Renewal Term 5 years            
Building (1)              
Property and Equipment, Gross $ 6.0 $ 6.0          
Property, Plant and Equipment [Member] | Building (1)              
Property and Equipment, Gross       $ 6.0      
Other Noncurrent Liabilities [Member] | Leased Buildings -232 South Dobson Road [Member]              
Financing lease obligations       $ 6.0      
Minimum [Member]              
Potential Rental Rate Adjustment Maximum 2.50%            
Maximum [Member]              
Potential Rental Rate Adjustment Maximum 4.00%