Revenue Recognition - Schedule of Revenues Disaggregated by Service Line (Detail) - USD ($)	3 Months Ended								12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Disaggregation Of Revenue [Line Items]
Total services	$ 147,024,000	$ 148,092,000	$ 146,970,000	$ 150,139,000	$ 151,084,000	$ 146,082,000	$ 148,176,000	$ 150,398,000	$ 592,225,000	$ 595,740,000	$ 558,350,000
Patient Management Services [Member]
Disaggregation Of Revenue [Line Items]
Total services									386,814,000	368,198,000
Network Solutions Services [Member]
Disaggregation Of Revenue [Line Items]
Total services									$ 205,411,000	$ 227,542,000