Divestiture of Assets - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended
	Mar. 31, 2018	Mar. 31, 2018	Mar. 31, 2017
Divestiture Of Assets [Line Items]
Loss on disposition of assets		$ (8,701)	$ 1,036
Puerto Rico [Member]
Divestiture Of Assets [Line Items]
Fair value of disposal group recorded within other assets	$ 12,500	$ 12,500
Loss on disposition of assets	$ 8,666