Annual report pursuant to Section 13 and 15(d)

Property, Equipment and Software - Additional Information (Detail)

v2.4.1.9
Property, Equipment and Software - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Property, Plant and Equipment [Line Items]      
Depreciation and amortization expense for property, equipment and software $ 18.9us-gaap_DepreciationDepletionAndAmortization $ 14.1us-gaap_DepreciationDepletionAndAmortization $ 13.0us-gaap_DepreciationDepletionAndAmortization
Carrying amount of capitalized development costs 32.5us-gaap_CapitalizedComputerSoftwareGross 21.6us-gaap_CapitalizedComputerSoftwareGross  
Accumulated Amortization 10.7us-gaap_CapitalizedComputerSoftwareAccumulatedAmortization 9.0us-gaap_CapitalizedComputerSoftwareAccumulatedAmortization  
Capitalization of software development costs 10.9us-gaap_CapitalizedComputerSoftwareAdditions 7.6us-gaap_CapitalizedComputerSoftwareAdditions  
Software      
Property, Plant and Equipment [Line Items]      
Depreciation and amortization expense for property, equipment and software $ 1.7us-gaap_DepreciationDepletionAndAmortization
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_ComputerSoftwareIntangibleAssetMember
$ 1.0us-gaap_DepreciationDepletionAndAmortization
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_ComputerSoftwareIntangibleAssetMember
$ 1.2us-gaap_DepreciationDepletionAndAmortization
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_ComputerSoftwareIntangibleAssetMember
Weighted-average useful life 4 years 3 months 18 days