Other Income (Loss), Net - Schedule of Other Income (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Other Income and Expenses [Abstract]
Gain (loss) on sales/distributions of ownership interests	$ 2,697	$ 0	$ 3,654	$ 46
Other	(139)	(15)	(229)	(151)
Total other income (loss), net	$ 2,558	$ (15)	$ 3,425	$ (105)