Basis of Presentation and Summary of Significant Accounting Policies - Disaggregation of Revenue by Each Payor Type (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of Revenue [Line Items]
Revenue	$ 175,638	$ 165,169	$ 351,696	$ 330,274
Commercial
Disaggregation of Revenue [Line Items]
Revenue	33,296	25,479	65,562	50,192
Medicare
Disaggregation of Revenue [Line Items]
Revenue	64,273	62,038	128,950	126,918
Medicaid
Disaggregation of Revenue [Line Items]
Revenue	68,482	68,450	138,146	134,897
Other third parties
Disaggregation of Revenue [Line Items]
Revenue	$ 9,587	$ 9,202	$ 19,038	$ 18,267

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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+ Details