Assets and Liabilities Held for Sale - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Impairment loss recognized on assets held for sale	$ 9,188
GPT
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Impairment loss recognized on assets held for sale		$ 2,190
Impairment loss on equity investment	3,486
Impairment losses on asset held for sale	$ 6,998