Interest Costs - Summary of Interest Costs (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Schedule Of Interest [Line Items]
Interest costs charged to expense	$ 24,928	$ 21,689	$ 49,908	$ 43,228
Amortization of deferred financing costs	1,048	903	2,083	1,799
Accretion of debt discount on Convertible Notes	5,368	4,812	10,592	9,493
Amortization of debt premium on Senior Secured Notes	(703)	(178)	(1,388)	(351)
Interest expense	30,641	27,226	61,195	54,169
Total interest costs	30,719	27,481	61,317	54,786
Property and Equipment [Member]
Schedule Of Interest [Line Items]
Interest costs capitalized	3	2	15	6
Software [Member]
Schedule Of Interest [Line Items]
Interest costs capitalized	$ 75	$ 253	$ 107	$ 611