Fair Value (Assets Measured on a Non-recurring Basis) (Details) $ in Thousands	Sep. 30, 2020 USD ($)	Mar. 31, 2020
Fair Value, Measurements, Nonrecurring | Measurement Input, Cap Rate | Valuation Technique, Discounted Cash Flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value capitalization rate	0.100
Outlet Collection, Riverwalk
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value capitalization rate		0.10
Outlet Collection, Riverwalk | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value Measurement	$ 46,794
Outlet Collection, Riverwalk | Fair Value, Measurements, Nonrecurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value Measurement	0
Outlet Collection, Riverwalk | Fair Value, Measurements, Nonrecurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value Measurement	0
Outlet Collection, Riverwalk | Fair Value, Measurements, Nonrecurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value Measurement	$ 46,794