Summary of Significant Accounting Policies - Disaggregated Revenue by Payor Type and Major Service (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
Disaggregation of Revenue [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
Contracted third-party payors
Disaggregation of Revenue [Line Items]
Revenue									$ 73,005	101,845	56,949
Non-contracted third-party payors
Disaggregation of Revenue [Line Items]
Revenue									$ 8,051	10,770	12,447
Centers for Medicare & Medicaid
Disaggregation of Revenue [Line Items]
Revenue										58,918	40,482
Healthcare Institutions
Disaggregation of Revenue [Line Items]
Revenue										$ 43,019	$ 37,399