Revenues (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Jan. 01, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 107,298,000
Capitalized commission fees, period	21 months
Impairment losses, capitalized commissions	$ 0
System One
Disaggregation of Revenue [Line Items]
Revenues	82,887,000
System One | Home
Disaggregation of Revenue [Line Items]
Revenues	58,679,000
System One | Critical Care
Disaggregation of Revenue [Line Items]
Revenues	24,208,000
In-Center
Disaggregation of Revenue [Line Items]
Revenues	17,357,000
Other
Disaggregation of Revenue [Line Items]
Revenues	2,820,000
Other | Products
Disaggregation of Revenue [Line Items]
Revenues	103,064,000
Other | Services
Disaggregation of Revenue [Line Items]
Revenues	5,419,000
Intersegment Elimination
Disaggregation of Revenue [Line Items]
Revenues	(1,185,000)
Prepaid Expenses and Other Current Assets
Disaggregation of Revenue [Line Items]
Capitalized commission fees	2,100,000	$ 2,000,000
Selling and marketing
Disaggregation of Revenue [Line Items]
Amortization expense, capitalized commissions	$ 600,000