Selected Quarterly Financial Data (unaudited) - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended								9 Months Ended	12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue	$ 59,104	$ 54,673	$ 52,441	$ 48,334	$ 41,782	$ 38,441	$ 35,292	$ 31,762		$ 214,552	$ 147,277	$ 99,129
As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue			$ 53,331	$ 47,214	$ 43,155		$ 35,469	$ 30,565			147,293	$ 98,509
Contracted third-party payors
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue									$ 73,005	101,845	56,949
Contracted third-party payors | Classification error of payors in the disaggregation of revenue
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue										965
Contracted third-party payors | As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue									72,040
Non-contracted third-party payors
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue									8,051	$ 10,770	$ 12,447
Non-contracted third-party payors | As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue									$ 9,016