Intangible Assets (Including Affiliate) - Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	$ 86,336
Finite-Lived Intangible Assets, Including Related Parties, Gross		$ 86,336
Less accumulated amortization	(35,966)
Finite-Lived Intangible Assets, Including Affiliates, Accumulated Amortization		(33,289)
Total intangible assets, net	$ 50,370	3,236
Finite-Lived Intangible Assets, Including Related Parties, Net		$ 53,047