Goodwill and intangible assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Indefinite-lived Intangible Assets [Line Items]
GrossCarryingAmount	$ 4,687	$ 2,709
AccumulatedAmortization	900	387
Net	$ 3,787	2,322
License Agreement Terms [Member]
Indefinite-lived Intangible Assets [Line Items]
Amortization Period(in years)	10 years
GrossCarryingAmount	$ 1,000	1,000
AccumulatedAmortization	117	17
Net	$ 883	983
Trade Names [Member]
Indefinite-lived Intangible Assets [Line Items]
Amortization Period(in years)	2 years
GrossCarryingAmount	$ 30	108
AccumulatedAmortization	24	9
Net	$ 6	99
Patents [Member]
Indefinite-lived Intangible Assets [Line Items]
Amortization Period(in years)	5 years
GrossCarryingAmount	$ 387	374
AccumulatedAmortization	352	332
Net	35	42
Noncompete Agreements [Member]
Indefinite-lived Intangible Assets [Line Items]
GrossCarryingAmount	1,270	1,000
AccumulatedAmortization	171	16
Net	$ 1,099	984
Noncompete Agreements [Member] | Maximum [Member]
Indefinite-lived Intangible Assets [Line Items]
Amortization Period(in years)	10 years
Noncompete Agreements [Member] | Minimum [Member]
Indefinite-lived Intangible Assets [Line Items]
Amortization Period(in years)	6 years
Customer Relationships [Member]
Indefinite-lived Intangible Assets [Line Items]
GrossCarryingAmount	$ 2,000	227
AccumulatedAmortization	236	13
Net	$ 1,764	$ 214
Customer Relationships [Member] | Maximum [Member]
Indefinite-lived Intangible Assets [Line Items]
Amortization Period(in years)	10 years
Customer Relationships [Member] | Minimum [Member]
Indefinite-lived Intangible Assets [Line Items]
Amortization Period(in years)	3 years