Line of Credit (Details)			9 Months Ended
	Feb. 02, 2019	Feb. 03, 2015 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)	Nov. 05, 2015 USD ($) tranche
Line of Credit Facility [Line Items]
Mortgage Loans on Real Estate, Principal Amount of Loan in Default			$ 3,151,000	$ 2,721,000
Wells Fargo, Merrill Lynch, Pierce Fenner & Smith, PNC Capital Markets Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of credit facility, interest rate at period end (percent)			1.82%	1.59%
Line of credit facility, remaining borrowing capacity			$ 150,000,000	$ 190,000,000	$ 300,000,000
Number of tranches in loan credit facility | tranche					2
Unsecured Debt [Member] | KeyBanc Capital Markets and J.P. Morgan Securities LLC [Member]
Line of Credit Facility [Line Items]
Debt instrument, face amount				200,000,000
Revolving Credit Facility [Member] | KeyBanc Capital Markets and J.P. Morgan Securities LLC Amended and Restated [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Initiation Date		Feb. 03, 2015
Extension option on line of credit, period			1 year
Line of Credit Facility, Interest Rate Description			1-month LIBOR plus 1.40%
Line of credit facility, remaining borrowing capacity		$ 300,000,000	$ 300,000,000	$ 300,000,000
Maximum [Member] | Wells Fargo, Merrill Lynch, Pierce Fenner & Smith, PNC Capital Markets Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of credit facility, remaining borrowing capacity					$ 600,000,000
Maximum [Member] | Revolving Credit Facility [Member] | KeyBanc Capital Markets and J.P. Morgan Securities LLC Amended and Restated [Member]
Line of Credit Facility [Line Items]
Line of credit facility, remaining borrowing capacity		$ 600,000,000
Scenario, Forecast [Member] | Revolving Credit Facility [Member] | KeyBanc Capital Markets and J.P. Morgan Securities LLC Amended and Restated [Member]
Line of Credit Facility [Line Items]
Commitment fee	0.15%
Debt Instrument, Maturity Date	Feb. 02, 2019
5-Year Tranche [Member] | Wells Fargo, Merrill Lynch, Pierce Fenner & Smith, PNC Capital Markets Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Interest Rate Description			LIBOR plus 1.30%
7-Year Tranche [Member] | Wells Fargo, Merrill Lynch, Pierce Fenner & Smith, PNC Capital Markets Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Interest Rate Description			1-month LIBOR plus 1.60%
One-Month LIBOR [Member] | Revolving Credit Facility [Member] | KeyBanc Capital Markets and J.P. Morgan Securities LLC Amended and Restated [Member]
Line of Credit Facility [Line Items]
Basis spread on variable interest rate (percent)			1.40%
One-Month LIBOR [Member] | 7-Year Tranche [Member] | Wells Fargo, Merrill Lynch, Pierce Fenner & Smith, PNC Capital Markets Credit Facility [Member]
Line of Credit Facility [Line Items]
Basis spread on variable interest rate (percent)			1.60%
London Interbank Offered Rate (LIBOR) [Member] | 5-Year Tranche [Member] | Wells Fargo, Merrill Lynch, Pierce Fenner & Smith, PNC Capital Markets Credit Facility [Member]
Line of Credit Facility [Line Items]
Basis spread on variable interest rate (percent)			1.30%