Segments, Concentrations and Geographic Information - Additional Information (Detail)	3 Months Ended	6 Months Ended
	Jun. 30, 2016 customer	Jun. 30, 2017 segment 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)		12.00%