Annual report pursuant to Section 13 and 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 $)
In Thousands, unless otherwise specified
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Property Plant And Equipment [Line Items]      
Depreciation and amortization $ 11,930us-gaap_Depreciation $ 8,341us-gaap_Depreciation $ 4,686us-gaap_Depreciation
Equipment      
Property Plant And Equipment [Line Items]      
Depreciation and amortization 10,339us-gaap_Depreciation
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_EquipmentMember 		7,132us-gaap_Depreciation
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_EquipmentMember 		4,056us-gaap_Depreciation
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_EquipmentMember
Other property and equipment      
Property Plant And Equipment [Line Items]      
Depreciation and amortization $ 1,591us-gaap_Depreciation
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_PropertyPlantAndEquipmentOtherTypesMember 		$ 1,209us-gaap_Depreciation
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_PropertyPlantAndEquipmentOtherTypesMember 		$ 630us-gaap_Depreciation
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_PropertyPlantAndEquipmentOtherTypesMember