For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Period Type:	duration

Summary of Significant Accounting Policies - Concentration of Credit Risk (Detail) - Medicare	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Revenues \| Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk percentage	61.00%	58.00%	60.00%	56.00%
Accounts Receivable \| Credit Concentration Risk
Concentration Risk [Line Items]
Concentration risk percentage			29.00%		28.00%