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Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

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Debt (Narrative) (Details)	Apr. 30, 2020 USD ($)	Mar. 22, 2019 USD ($)	Jan. 31, 2019 USD ($)	Nov. 07, 2014 USD ($)	Sep. 30, 2020 USD ($) property	Mar. 20, 2020 USD ($)
Debt Instrument [Line Items]
Secured debt					$ 161,000,000.0
Number of collateralized properties (in collateralized properties) \| property					7
Carrying value of collateralized properties					$ 251,700,000
U.S. Bank National Association [Member]
Debt Instrument [Line Items]
Line of credit outstanding	$ 1,733,510
Interest rate	1.00%
Monthly payments	$ 96,864.28
2019 Facility [Member]
Debt Instrument [Line Items]
Credit facility, covenant, total debt to total assets ratio, maximum			0.60
Credit facility, covenant, secured debt to total asset ratio, maximum			0.40
Credit facility, covenant, EBITDA to fixed charges ratio, minimum			1.50
Credit facility, covenant, other recourse debt to total assets ratio, maximum			0.15
Credit facility, interest rate at period end					1.81%
Repayments of long-term debt			$ 446,200,000
Covenant, tangible net worth threshold before percentage of aggregate net proceeds, amount			$ 372,000,000
Covenant, tangible net worth, percentage of aggregate net proceeds, minimum			75.00%
Series A Senior Notes [Member]
Debt Instrument [Line Items]
Annual principal payment		$ 7,100,000
Series B Senior Notes [Member]
Debt Instrument [Line Items]
Annual principal payment		10,000,000.0
Senior Notes [Member]
Debt Instrument [Line Items]
Face amount of debt		100,000,000
Periodic payment, principal		$ 1,000,000
Credit facility, covenant, total debt to total assets ratio, maximum		0.60
Credit facility, covenant, secured debt to total asset ratio, maximum		0.40
Credit facility, covenant, EBITDA to fixed charges ratio, minimum		1.50
Credit facility, covenant, other recourse debt to total assets ratio, maximum		0.15
Covenant, tangible net worth threshold before percentage of aggregate net proceeds, amount		$ 372,000,000
Covenant, tangible net worth, percentage of aggregate net proceeds, minimum		75.00%
Senior Notes [Member] \| Series A Senior Notes [Member]
Debt Instrument [Line Items]
Face amount of debt		$ 50,000,000
Stated interest rate		5.09%
Senior Notes [Member] \| Series B Senior Notes [Member]
Debt Instrument [Line Items]
Face amount of debt		$ 50,000,000
Stated interest rate		5.17%
Revolving Credit Facility [Member] \| 2019 Facility [Member]
Debt Instrument [Line Items]
Line of credit outstanding					$ 404,500,000	$ 30,000,000.0
Credit facility, remaining borrowing capacity					$ 13,000,000.0
Revolving Credit Facility [Member] \| 2019 Facility [Member] \| LIBOR Rate
Debt Instrument [Line Items]
Basis spread on variable rate			1.00%
Revolving Credit Facility [Member] \| 2019 Facility [Member] \| LIBOR Rate \| Minimum [Member]
Debt Instrument [Line Items]
Basis spread on variable rate			1.40%
Revolving Credit Facility [Member] \| 2019 Facility [Member] \| LIBOR Rate \| Maximum [Member]
Debt Instrument [Line Items]
Basis spread on variable rate			1.90%
Revolving Credit Facility [Member] \| 2018 Facility [Member] \| LIBOR Rate
Debt Instrument [Line Items]
Basis spread on variable rate				1.00%
Revolving Credit Facility [Member] \| 2018 Facility [Member] \| LIBOR Rate \| Minimum [Member]
Debt Instrument [Line Items]
Basis spread on variable rate				1.40%
Revolving Credit Facility [Member] \| 2018 Facility [Member] \| LIBOR Rate \| Maximum [Member]
Debt Instrument [Line Items]
Basis spread on variable rate				1.95%
Revolving Credit Facility [Member] \| The Revolver [Member]
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity				$ 300,000,000
Term Loan [Member] \| 2019 Facility [Member] \| LIBOR Rate \| Minimum [Member]
Debt Instrument [Line Items]
Basis spread on variable rate			1.35%
Term Loan [Member] \| 2019 Facility [Member] \| LIBOR Rate \| Maximum [Member]
Debt Instrument [Line Items]
Basis spread on variable rate			1.90%
Term Loan [Member] \| 2018 Facility [Member] \| LIBOR Rate \| Minimum [Member]
Debt Instrument [Line Items]
Basis spread on variable rate				1.35%
Term Loan [Member] \| 2018 Facility [Member] \| LIBOR Rate \| Maximum [Member]
Debt Instrument [Line Items]
Basis spread on variable rate				2.25%
Term Loan [Member] \| Term Loan 1 [Member]
Debt Instrument [Line Items]
Face amount of debt				$ 50,000,000
Term Loan [Member] \| Term Loan 2 [Member]
Debt Instrument [Line Items]
Face amount of debt				50,000,000
Term Loan [Member] \| Term Loan 3 [Member]
Debt Instrument [Line Items]
Face amount of debt				100,000,000
Credit facility, remaining borrowing capacity				$ 100,000,000
Term Loan [Member] \| Unsecured Line Of Credit [Member] \| Term Loan A [Member]
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity			$ 165,000,000.0
Term Loan [Member] \| Unsecured Line Of Credit [Member] \| Term Loan B [Member]
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity			100,000,000.0
Revolving Credit Facility [Member] \| 2019 Facility [Member]
Debt Instrument [Line Items]
Credit facility, accordion feature, increase limit			200,000,000.0
Revolving Credit Facility [Member] \| Unsecured Line Of Credit [Member] \| 2019 Revolver [Member]
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity			$ 250,000,000.0