Quarterly Financial Information (unaudited) - Summary of Selected Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								6 Months Ended	12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Total revenue	$ 53,678	$ 64,048	$ 57,893	$ 65,398	$ 66,196	$ 57,607	$ 61,867	$ 63,004	$ 113,571	$ 241,017	$ 248,674
Operating (loss) income	(65,163)	(17,997)	(14,665)	(16,742)	(10,837)	(22,771)	2,765	396	(9,373)	(114,567)	(30,447)
Net (loss) income	(70,378)	17,276	(34,867)	(32,844)	(26,483)	(37,247)	(12,565)	(14,714)	(38,803)	(120,813)	(91,009)
Net (loss) income attributable to common shareholders	$ (43,456)	$ 10,514	$ (21,219)	$ (19,838)	$ (15,004)	$ (21,102)	$ (7,117)	$ (8,335)	$ (22,338)	$ (73,999)	$ (51,558)
Net (loss) income per share attributable to Class A and Class C common shareholders - Basic	$ (1.27)	$ 0.31	$ (0.63)	$ (0.59)	$ (0.48)	$ (0.67)	$ (0.23)	$ (0.27)
Net (loss) income per share attributable to Class A and Class C common shareholders - Diluted	$ (1.27)	$ 0.31	$ (0.63)	$ (0.59)	$ (0.48)	$ (0.67)	$ (0.23)	$ (0.27)
Weighted average Class A and Class C common shares outstanding - Basic	34,094	33,841	33,766	33,510	31,418	31,419	31,391	31,391
Weighted average Class A and Class C common shares outstanding - Diluted	34,094	33,841	33,766	33,510	31,418	31,419	31,391	31,391