Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Summary of Depreciation and Amortization Expense of Property and Equipment and Rental Equipment (Details)

v2.4.1.9
Summary of Significant Accounting Policies - Summary of Depreciation and Amortization Expense of Property and Equipment and Rental Equipment (Details) (USD $)
 3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Property Plant And Equipment [Line Items]    
Depreciation and amortization $ 3,423,000us-gaap_Depreciation $ 2,619,000us-gaap_Depreciation
Equipment    
Property Plant And Equipment [Line Items]    
Depreciation and amortization 2,956,000us-gaap_Depreciation
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_EquipmentMember 		2,257,000us-gaap_Depreciation
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_EquipmentMember
Other property and equipment    
Property Plant And Equipment [Line Items]    
Depreciation and amortization $ 467,000us-gaap_Depreciation
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_PropertyPlantAndEquipmentOtherTypesMember 		$ 362,000us-gaap_Depreciation
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_PropertyPlantAndEquipmentOtherTypesMember