Quarterly report pursuant to Section 13 or 15(d)

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

v2.4.1.9
Summary of Significant Accounting Policies - Summary of Property Plant and Equipment and Rental Equipment with Associated Accumulated Depreciation (Details) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Property Plant And Equipment [Line Items]    
Property and equipment $ 61,090us-gaap_PropertyPlantAndEquipmentGross $ 57,767us-gaap_PropertyPlantAndEquipmentGross
Accumulated depreciation 28,762us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment 25,840us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
Property and equipment, net 32,328us-gaap_PropertyPlantAndEquipmentNet 31,927us-gaap_PropertyPlantAndEquipmentNet
Equipment    
Property Plant And Equipment [Line Items]    
Property and equipment 51,130us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_EquipmentMember
48,359us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_EquipmentMember
Accumulated depreciation 23,539us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_EquipmentMember
21,084us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_EquipmentMember
Property and equipment, net 27,591us-gaap_PropertyPlantAndEquipmentNet
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_EquipmentMember
27,275us-gaap_PropertyPlantAndEquipmentNet
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_EquipmentMember
Other property and equipment    
Property Plant And Equipment [Line Items]    
Property and equipment 9,960us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_PropertyPlantAndEquipmentOtherTypesMember
9,408us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_PropertyPlantAndEquipmentOtherTypesMember
Accumulated depreciation 5,223us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_PropertyPlantAndEquipmentOtherTypesMember
4,756us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_PropertyPlantAndEquipmentOtherTypesMember
Property and equipment, net $ 4,737us-gaap_PropertyPlantAndEquipmentNet
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_PropertyPlantAndEquipmentOtherTypesMember
$ 4,652us-gaap_PropertyPlantAndEquipmentNet
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_PropertyPlantAndEquipmentOtherTypesMember