Ownership, Description of Business, and Summary of Significant Accounting Policies - Estimated Useful Lives of Property and Equipment (Detail) |
12 Months Ended |
---|---|
Dec. 31, 2017 | |
Leasehold improvements | |
Property, Plant and Equipment [Line Items] | |
Leasehold improvements | Lesser of lease term, including periods covered by renewal options, or useful life |
Furniture, fixtures and equipment | Minimum | |
Property, Plant and Equipment [Line Items] | |
Estimated useful life | 5 years |
Furniture, fixtures and equipment | Maximum | |
Property, Plant and Equipment [Line Items] | |
Estimated useful life | 10 years |
Computer hardware and software | Minimum | |
Property, Plant and Equipment [Line Items] | |
Estimated useful life | 3 years |
Computer hardware and software | Maximum | |
Property, Plant and Equipment [Line Items] | |
Estimated useful life | 5 years |