Quarterly Results of Operations - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Effect Of Fourth Quarter Events [Line Items]
Pre-tax income related to insurance recoveries					$ 200	$ 100	$ 300	$ 3,100	$ 443	$ 3,657	$ 10,368
Adjustment to the reserve for uncertain tax positions, net								$ 3,000
Basic and diluted net income (loss) per share	$ 0.20	$ 0.15	$ 0.02	$ (0.05)	$ (0.11)	$ 0.02	$ (0.60)	$ 0.21	$ 0.31	$ (0.49)	$ 0.59
Workforce Reduction Charges
Effect Of Fourth Quarter Events [Line Items]
Basic and diluted net income (loss) per share							(0.07)
Other-Than-Temporary Impairment Charge in Marketable Equity Security
Effect Of Fourth Quarter Events [Line Items]
Basic and diluted net income (loss) per share						$ (0.03)
Insurance Settlement Gains
Effect Of Fourth Quarter Events [Line Items]
Basic and diluted net income (loss) per share				$ 0.01
Execution and Finalization of Agreement | US-Canada APA
Effect Of Fourth Quarter Events [Line Items]
Basic and diluted net income (loss) per share	(0.01)	$ 0.02
Increase (Decrease) in Uncertain Tax Positions
Effect Of Fourth Quarter Events [Line Items]
Basic and diluted net income (loss) per share	(0.01)
Deferred Income Tax Asset Valuation Allowance
Effect Of Fourth Quarter Events [Line Items]
Basic and diluted net income (loss) per share	$ 0.02		$ (0.01)				$ (0.65)