Debt and Financial Instruments - Additional Information (Detail)			3 Months Ended				9 Months Ended		12 Months Ended	33 Months Ended	36 Months Ended
	Apr. 02, 2019 USD ($)	Mar. 27, 2018 USD ($) Option	Sep. 30, 2019 USD ($) Derivative	Mar. 31, 2019 USD ($)	Sep. 30, 2016 USD ($) Derivative	Jun. 30, 2016 USD ($) Derivative	Sep. 30, 2019 USD ($) Derivative	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)	Mar. 31, 2019 USD ($)	Mar. 31, 2019 USD ($)
Debt Instrument [Line Items]
Outstanding borrowings under revolving credit agreement			$ 205,650,000				$ 205,650,000		$ 196,400,000
Available borrowing capacity			$ 94,300,000				94,300,000		103,600,000
Repayments of mortgage loan							$ 3,775,000	$ 22,964,000
Interest Rate Swap
Debt Instrument [Line Items]
Number of interest rate cap agreements | Derivative			1				1
Derivative instruments, fixed rate			1.144%				1.144%
Notional amount			$ 50,000,000				$ 50,000,000
Expiration date of interest rate			Sep. 16, 2024
Interest Rate Cap
Debt Instrument [Line Items]
Number of interest rate cap agreements | Derivative					1	1
Notional amount					$ 30,000,000	$ 30,000,000
Expiration date of interest rate					Mar. 31, 2019	Mar. 31, 2019
Derivative interest rate cap, payment received or accrued from counterparties				$ 61,000					144,000	$ 205,000	$ 205,000
Premium paid					$ 55,000	$ 115,000
Level 2
Debt Instrument [Line Items]
Mortgage loan fair value			$ 63,900,000				63,900,000		64,900,000
Mortgage debt									$ 65,300,000
Level 2 | Interest Rate Swap
Debt Instrument [Line Items]
Asset derivatives, fair value			560,595				$ 560,595
Derivative interest rate cap, payment received or accrued from counterparties			17,000
Vibra Hospital-Corpus Christi Fixed Rate Mortgage Loan
Debt Instrument [Line Items]
Repayments of mortgage loan	$ 2,500,000
Lease expiration date							Jun. 01, 2019
LIBOR | Interest Rate Cap
Debt Instrument [Line Items]
Derivative instruments, LIBOR rate					1.50%	1.50%
Credit Agreement
Debt Instrument [Line Items]
Outstanding borrowing		$ 300,000,000	$ 300,000,000				$ 300,000,000
Increase in borrowing capacity		$ 50,000,000
Unsecured revolving amended credit agreement terminated date		2022-03
Number of additional six month extension options | Option		2
Proceeds from Lines of Credit		$ 50,000,000
Credit facility, Interest Rate Terms							one, two, three, or six-month LIBOR plus an applicable margin ranging from 1.10% to 1.35% or at the Base Rate plus an applicable margin ranging from 0.10% to 0.35%.
Base rate description							the greater of: (a) the administrative agent’s prime rate; (b) the federal funds effective rate plus 1/2 of 1%, and; (c) one month LIBOR plus 1%.
Facility fee payable on commitment							0.20%
Credit Agreement | LIBOR
Debt Instrument [Line Items]
Margin points added to the reference rate							1.20%
Credit Agreement | Base Rate
Debt Instrument [Line Items]
Margin points added to the reference rate							0.20%
Credit Agreement | Swingline/Short-Term Loans
Debt Instrument [Line Items]
Outstanding borrowing		30,000,000
Credit Agreement | Letters of Credit
Debt Instrument [Line Items]
Outstanding borrowing		$ 40,000,000
Credit Agreement | Minimum
Debt Instrument [Line Items]
Facility fee payable on commitment		0.15%
Credit Agreement | Minimum | LIBOR
Debt Instrument [Line Items]
Margin points added to the reference rate		1.10%
Margin points added to the base rate		1.00%
Credit Agreement | Minimum | Base Rate
Debt Instrument [Line Items]
Margin points added to the reference rate		0.10%
Credit Agreement | Minimum | Federal Funds Effective Rate
Debt Instrument [Line Items]
Margin points added to the base rate		0.50%
Credit Agreement | Maximum
Debt Instrument [Line Items]
Facility fee payable on commitment		0.35%
Credit Agreement | Maximum | LIBOR
Debt Instrument [Line Items]
Margin points added to the reference rate		1.35%
Credit Agreement | Maximum | Base Rate
Debt Instrument [Line Items]
Margin points added to the reference rate		0.35%