Real Estate - Additional Information (Detail) ft² in Thousands	1 Months Ended	3 Months Ended			9 Months Ended
	Dec. 31, 2007 USD ($) Building	Sep. 30, 2016 USD ($) RenewalOptions	Mar. 31, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) ft² RenewalOptions Lease_Agreements	Sep. 30, 2015 USD ($)	Dec. 31, 2008 USD ($)
Real Estate Properties [Line Items]
Sale of facility and associated real property	$ 109,000,000
Mortgage debt retired	47,700,000
Cash received net of transaction costs and debt retirement	$ 61,000,000
Leaseback transaction lease period	12 years
Number of building leased | Building	2
Net deferred gain on real estate sale		$ 11,800,000			$ 11,800,000		$ 39,100,000
Deferred gain recognized on real estate sale		900,000		$ 800,000	$ 2,600,000	$ 2,500,000
Lease expiration year					2019
Percentage of management fee included in the base annual rent					3.50%
Letter of credit		$ 4,600,000			$ 4,600,000
Lease extension period					10 years
Number of times to renew the lease contract | RenewalOptions		2			2
Subleased area | ft²					16
Rental income from sublease agreement					$ 600,000
Increase in deferred rent					$ (208,000)	$ 25,000
Sublease
Real Estate Properties [Line Items]
Number of sublease agreements | Lease_Agreements					1
Lease renewal additional periods					1 year
Reversal of cease use expense			$ 800,000
Increase in deferred rent			$ 246,000
Second Sublease
Real Estate Properties [Line Items]
Lease renewal additional periods					1 year
Lease expiration date					2018-03