Segments, Concentrations and Geographic Information - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2017 segment customer	Mar. 31, 2016 customer
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of business segments | segment	3
Sales Revenue, Net [Member] | Customer Concentration Risk [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of major customers	0	0
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | Minimum [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk (as percent)	10.00%	10.00%
Gearing [Member] | Sales Revenue, Net [Member] | Customer Concentration Risk [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of major customers	1
Concentration risk (as percent)	10.00%