Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017 USD ($) Project Source Method	Dec. 31, 2016 USD ($) Project	Dec. 31, 2015 USD ($)
Accounting Policies [Line Items]
Inventory reserves	$ (83,566,000)	$ (45,648,000)
Impairments and other charges related to inventory	33,600,000
Impairments and other charges related to fixed sssets	27,400,000
Impairments of long-lived assets	$ 0	0	$ 0
Number of product revenue sources | Method	2
Unbilled receivables	$ 41,000,000	$ 56,800,000
Number of projects | Project	8	10
Percentage of total revenues	13.00%	14.00%
Percentage of product revenues	16.00%	17.00%
Number of service revenue sources | Source	3
Gains in foreign currency exchange transactions	$ (12,700,000)	$ 25,600,000	$ 3,900,000
Inventories
Accounting Policies [Line Items]
Inventory reserves	$ (83,500,000)	$ (45,600,000)