Ownership, Description of Business, and Summary of Significant Accounting Policies - Estimated Useful Lives of Property and Equipment (Detail)	12 Months Ended
	Dec. 31, 2016
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Leasehold improvements	Lesser of lease term, including periods covered by renewal options, or useful life
Minimum [Member] | Furniture, Fixtures and Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Minimum [Member] | Computer Hardware and Software [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Maximum [Member] | Furniture, Fixtures and Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years
Maximum [Member] | Computer Hardware and Software [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years