Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Summary of Property Plant and Equipment and Rental Equipment with Related Accumulated Depreciation (Details)

v2.4.1.9
Summary of Significant Accounting Policies - Summary of Property Plant and Equipment and Rental Equipment with Related Accumulated Depreciation (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Property Plant And Equipment [Line Items]    
Property and equipment $ 57,767us-gaap_PropertyPlantAndEquipmentGross $ 45,678us-gaap_PropertyPlantAndEquipmentGross
Accumulated depreciation 25,840us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment 15,956us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
Property and equipment, net 31,927us-gaap_PropertyPlantAndEquipmentNet 29,722us-gaap_PropertyPlantAndEquipmentNet
Equipment    
Property Plant And Equipment [Line Items]    
Property and equipment 48,359us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_EquipmentMember
37,573us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_EquipmentMember
Accumulated depreciation 21,084us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_EquipmentMember
12,545us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_EquipmentMember
Property and equipment, net 27,275us-gaap_PropertyPlantAndEquipmentNet
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_EquipmentMember
25,028us-gaap_PropertyPlantAndEquipmentNet
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_EquipmentMember
Other property and equipment    
Property Plant And Equipment [Line Items]    
Property and equipment 9,408us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_PropertyPlantAndEquipmentOtherTypesMember
8,105us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_PropertyPlantAndEquipmentOtherTypesMember
Accumulated depreciation 4,756us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_PropertyPlantAndEquipmentOtherTypesMember
3,411us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_PropertyPlantAndEquipmentOtherTypesMember
Property and equipment, net $ 4,652us-gaap_PropertyPlantAndEquipmentNet
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_PropertyPlantAndEquipmentOtherTypesMember
$ 4,694us-gaap_PropertyPlantAndEquipmentNet
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_PropertyPlantAndEquipmentOtherTypesMember