Fair Value Measures - Items Measured at Fair Value on a Non-Recurring Basis (Details)	9 Months Ended
	Sep. 30, 2020 USD ($) property	Sep. 30, 2019 USD ($) property
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Properties impaired | property	47	53
Impairment charges | $	$ 36,900,000	$ 24,200,000
COVID-19 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Properties impaired, watch list | property	5
Impairment charges | $	$ 0
Measurement Input, Discount Rate [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement Input	0.079
Measurement Input, Discount Rate [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement Input	0.086
Measurement Input, Discount Rate [Member] | Weighted Average [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement Input	0.083
Measurement Input, Cap Rate [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement Input	0.074
Measurement Input, Cap Rate [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement Input	0.081
Measurement Input, Cap Rate [Member] | Weighted Average [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement Input	0.078