Summary of Significant Accounting Policies - Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2015
Equipment | Min
Property, Plant and Equipment
Useful life (in years)	3 years
Equipment | Max
Property, Plant and Equipment
Useful life (in years)	5 years
Rental equipment | Min
Property, Plant and Equipment
Useful life (in years)	5 years
Rental equipment | Max
Property, Plant and Equipment
Useful life (in years)	6 years
Leasehold improvements | Min
Property, Plant and Equipment
Useful life (in years)	3 years
Leasehold improvements | Max
Property, Plant and Equipment
Useful life (in years)	10 years
Capitalized software and website development costs
Property, Plant and Equipment
Useful life (in years)	3 years