Debt - Senior Unsecured Credit Facility and Unsecured Term Loans (Details)		3 Months Ended		9 Months Ended			10 Months Ended	19 Months Ended
	Jun. 09, 2020	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2021	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2021	Apr. 01, 2021	Aug. 14, 2020 USD ($)	Dec. 31, 2019 USD ($)
Line of Credit Facility [Line Items]
Percent of unused portion line of credit facility triggering lower commitment fee (as a percent)					50.00%
Senior unsecured credit facility		$ 99,985,000			$ 99,985,000						$ 75,000,000
Maximum annual preferred dividends										$ 17,500,000
Unsecured Term Loan
Line of Credit Facility [Line Items]
Interest incurred on the facility		3,700,000	$ 3,500,000		$ 9,800,000	$ 10,400,000
Minimum
Line of Credit Facility [Line Items]
Line of credit facility, unused capacity, commitment fee (as a percent)					0.20%
Maximum
Line of Credit Facility [Line Items]
Line of credit facility, unused capacity, commitment fee (as a percent)					0.30%
Revolving Credit Facility | Line of Credit
Line of Credit Facility [Line Items]
Maximum borrowing capacity		400,000,000			$ 400,000,000
Senior unsecured credit facility		99,985,000			99,985,000						75,000,000
Interest and unused credit facility fees		1,100,000	$ 1,100,000		$ 3,600,000	$ 2,800,000
Revolving Credit Facility | LIBOR | Line of Credit
Line of Credit Facility [Line Items]
Basis spread on variable rate					2.40%
Revolving Credit Facility | LIBOR | Minimum | Line of Credit
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.25%
Unsecured Term Loan due July 2024 | Unsecured Term Loan
Line of Credit Facility [Line Items]
Principal balance		350,000,000			$ 350,000,000						350,000,000
Unsecured Term Loan due July 2024 | LIBOR | Unsecured Term Loan
Line of Credit Facility [Line Items]
Basis spread on variable rate					2.35%
Unsecured Term Loan Due October 2023 | Unsecured Term Loan
Line of Credit Facility [Line Items]
Principal balance		$ 50,000,000			$ 50,000,000						$ 50,000,000
Unsecured Term Loan Due October 2023 | LIBOR | Unsecured Term Loan
Line of Credit Facility [Line Items]
Basis spread on variable rate					2.35%
Forecast
Line of Credit Facility [Line Items]
Minimum liquidity covenant							$ 100,000,000.0
Covenant, acquisition limitation							$ 300,000,000
Maximum leverage ratio (as a percent)							0.60		0.65
Unencumbered leverage ratio							60.00%		65.00%
Forecast | Revolving Credit Facility | LIBOR | Line of Credit
Line of Credit Facility [Line Items]
Basis spread on variable rate								2.40%
Forecast | Unsecured Term Loan Due October 2023 | LIBOR | Unsecured Term Loan
Line of Credit Facility [Line Items]
Basis spread on variable rate								2.35%
Testing Period One | Forecast | Minimum
Line of Credit Facility [Line Items]
Unencumbered implied debt service coverage ratio				1.00
Testing Period Two | Forecast | Minimum
Line of Credit Facility [Line Items]
Unencumbered implied debt service coverage ratio				1.00
Testing Period Three | Forecast | Minimum
Line of Credit Facility [Line Items]
Unencumbered implied debt service coverage ratio				1.10
Testing Periods Thereafter | Forecast | Minimum
Line of Credit Facility [Line Items]
Unencumbered implied debt service coverage ratio				1.20