Revenue - Additional Information (Detail) - CARES Act [Member] - Medicare [Member] - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Apr. 30, 2020	Jun. 30, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Repayment of advanced payments period	2022-06
Repayment of advanced payments		$ 7.0
CMS' Accelerated and Advance Payment Program [Member]
Disaggregation of Revenue [Line Items]
Amount of advance payment received	$ 45.0
Repayment of advanced payments description	In April 2020, the Company received approximately $45 million from CMS’ Accelerated and Advance Payment Program for Medicare providers. The Company repaid approximately $7 million of the $45 million of advance payments during the second quarter of 2021 via recoupment from the Company’s new Medicare claims and will continue to repay the remaining balance on a monthly basis through June 2022.
Repayment of advanced payments period	2022-06
Repayment of advanced payments		7.0
CMS' Accelerated and Advance Payment Program [Member] | Other Accrued Liabilities [Member]
Disaggregation of Revenue [Line Items]
Contract liabilities		$ 41.3	$ 35.9
CMS' Accelerated and Advance Payment Program [Member] | Other Liabilities [Member]
Disaggregation of Revenue [Line Items]
Contract liabilities			$ 11.3