Amortization expense (Detail)

Amortization expense (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Intangible assets, amortization expense	$ 5,149us-gaap_AmortizationOfIntangibleAssets	$ 2,859us-gaap_AmortizationOfIntangibleAssets	$ 266us-gaap_AmortizationOfIntangibleAssets
Patents And Trade Names
Finite-Lived Intangible Assets [Line Items]
Intangible assets, amortization expense	688	388	109
Patents And Trade Names \| Minimum
Finite-Lived Intangible Assets [Line Items]
Intangible assets, estimated useful life	12 years
Patents And Trade Names \| Maximum
Finite-Lived Intangible Assets [Line Items]
Intangible assets, estimated useful life	17 years
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Intangible assets, amortization expense	1,694	761	116
Customer Relationships \| Minimum
Finite-Lived Intangible Assets [Line Items]
Intangible assets, estimated useful life	10 years
Customer Relationships \| Maximum
Finite-Lived Intangible Assets [Line Items]
Intangible assets, estimated useful life	15 years
Customer Contracts
Finite-Lived Intangible Assets [Line Items]
Intangible assets, amortization expense	56	1,613
Customer Contracts \| Minimum
Finite-Lived Intangible Assets [Line Items]
Intangible assets, estimated useful life	1 year
Customer Contracts \| Maximum
Finite-Lived Intangible Assets [Line Items]
Intangible assets, estimated useful life	3 years
Technology
Finite-Lived Intangible Assets [Line Items]
Intangible assets, amortization expense	129	67
Intangible assets, estimated useful life	10 years
Favorable Leases
Finite-Lived Intangible Assets [Line Items]
Intangible assets, amortization expense	61	3
Intangible assets, estimated useful life	10 years
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Intangible assets, amortization expense	141	10
Intangible assets, estimated useful life	6 years
Backlog
Finite-Lived Intangible Assets [Line Items]
Intangible assets, amortization expense	2,369
Intangible assets, estimated useful life	1 year
Product Certification
Finite-Lived Intangible Assets [Line Items]
Intangible assets, amortization expense	$ 11	$ 17	$ 41
Intangible assets, estimated useful life	3 years

Annual report pursuant to Section 13 and 15(d)

Amortization expense (Detail)