Revenue from Contracts with Customers - Impact of Adoption of Asc 606 on Company's Condensed Consolidated Balance Sheet and Condensed Consolidated Statement of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Jan. 01, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net	$ 8,123			$ 8,852
Accumulated deficit	(315,630)			$ (305,056)
Total revenues	11,281	$ 29,478
Net loss attributable to common stockholders	(10,709)	$ 48,325
Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net			$ 8,987
Accumulated deficit			(304,921)
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net	7,798
Accumulated deficit	(315,955)
Total revenues	11,091
Net loss attributable to common stockholders	(10,899)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable, net	325		135
Accumulated deficit	325		$ 135
Total revenues	190
Net loss attributable to common stockholders	$ 190