Asset acquisitions - Summary of Asset Acquisitions (Detail) - Anesthesia Services [Member] - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Consideration	$ 17,506,700	$ 27,509,811
Anesthesia Care Associates LLC [Member]
Business Acquisition [Line Items]
Date Acquired	2019-01
Consideration	$ 5,355,028
South Metro Anesthesia Associates LLC [Member]
Business Acquisition [Line Items]
Date Acquired	2019-05
Consideration	$ 1,791,431
Crystal River Anesthesia Associates, LLC [Member]
Business Acquisition [Line Items]
Date Acquired	2019-07
Consideration	$ 2,174,003
Triad Sedation Associates LLC [Member]
Business Acquisition [Line Items]
Date Acquired	2019-11
Consideration	$ 5,423,936
Consideration	$ 3,828,661
Florida Panhandle Anesthesia Associates LLC [Member]
Business Acquisition [Line Items]
Date Acquired	2019-12
Consideration	$ 2,762,302
Shreveport Sedation Associates LLC [Member]
Business Acquisition [Line Items]
Date Acquired		2018-03
Consideration		$ 9,495,184
Western Ohio Sedation Associates LLC [Member]
Business Acquisition [Line Items]
Date Acquired		2018-05
Consideration		$ 6,483,698
Lake Washington Anesthesia LLC [Member]
Business Acquisition [Line Items]
Date Acquired		2018-07
Consideration		$ 5,041,939
Lake Erie Sedation Associates LLC [Member]
Business Acquisition [Line Items]
Date Acquired		2018-09
Consideration		$ 4,233,115
Tennessee Valley Anesthesia Associates LLC [Member]
Business Acquisition [Line Items]
Date Acquired		2018-12
Consideration		$ 2,255,875