Property and Equipment - Schedule of Cost Basis and Estimated Useful Lives of Property and Equipment (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Computer hardware and software	[1]	$ 40,587	$ 27,660
Leasehold improvements	[1]	56,095	58,294
Furniture, fixtures and equipment	[1]	23,071	23,145
Building and improvements	[1]	8,485	8,485
Library materials	[1]	24	171
Vehicles	[1]	56	56
Construction in progress	[1]	823	1,128
Property plant and equipment, Total	[1]	129,141	118,939
Less-accumulated depreciation	[1]	(101,380)	(92,933)
Total property and equipment, net	[1]	$ 27,761	$ 26,006
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful life (in years)	[1]	Shorter of Life of Lease or Useful Life
Computer Hardware and Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful life (in years)	[1]	3 years
Furniture, Fixtures and Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful life (in years)	[1]	5 years
Furniture, Fixtures and Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful life (in years)	[1]	10 years
Building and Improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful life (in years)		15 years
Building and Improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful life (in years)		35 years
Library Materials [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful life (in years)	[1]	10 years
Vehicles [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful life (in years)	[1]	5 years

[1] Property and equipment which were fully depreciated and no longer in use by the Company were retired during the years ended December 31, 2020 and 2019; therefore, both the cost of the asset and the related accumulated depreciation balances were reduced to zero for these assets.