Fair Value Measurements - Fair Value Inputs of Long-Lived Assets Held and Used (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2020 ft² Property $ / ft²	Dec. 31, 2019 ft² Property $ / ft²
Fair Value Estimated Using Comparable Properties | Retail
Impaired Long Lived Assets Held Used And Held For Sale Properties [Line Items]
Number Of Properties Accounted For At Fair Value | Property	14	4
Fair Value Estimated Using Comparable Properties | Retail | Weighted Average
Impaired Long Lived Assets Held Used And Held For Sale Properties [Line Items]
Weighted Average Price (in dollars per sq ft)	47.89	104.84
Fair Value Estimated Using Comparable Properties | Retail | Measurement Input, Price Per Square Foot | Minimum
Impaired Long Lived Assets Held Used And Held For Sale Properties [Line Items]
Price per square foot range	4.35	34.45
Fair Value Estimated Using Comparable Properties | Retail | Measurement Input, Price Per Square Foot | Maximum
Impaired Long Lived Assets Held Used And Held For Sale Properties [Line Items]
Price per square foot range	740.74	740.74
Fair Value Estimated Using Comparable Properties | Retail | Measurement Input Square Footage
Impaired Long Lived Assets Held Used And Held For Sale Properties [Line Items]
Square Footage | ft²	533,803	35,885
Fair Value Estimated Using Listing Price or Broker Opinion of Value | Retail
Impaired Long Lived Assets Held Used And Held For Sale Properties [Line Items]
Number Of Properties Accounted For At Fair Value | Property	5	10
Fair Value Estimated Using Listing Price or Broker Opinion of Value | Retail | Weighted Average
Impaired Long Lived Assets Held Used And Held For Sale Properties [Line Items]
Weighted Average Price (in dollars per sq ft)	33.27	50.71
Fair Value Estimated Using Listing Price or Broker Opinion of Value | Retail | Measurement Input, Price Per Square Foot | Minimum
Impaired Long Lived Assets Held Used And Held For Sale Properties [Line Items]
Price per square foot range	2.50	24.78
Fair Value Estimated Using Listing Price or Broker Opinion of Value | Retail | Measurement Input, Price Per Square Foot | Maximum
Impaired Long Lived Assets Held Used And Held For Sale Properties [Line Items]
Price per square foot range	222.02	323.00
Fair Value Estimated Using Listing Price or Broker Opinion of Value | Retail | Measurement Input Square Footage
Impaired Long Lived Assets Held Used And Held For Sale Properties [Line Items]
Square Footage | ft²	338,484	165,773
Fair Value Estimated Using Listing Price or Broker Opinion of Value | Industrial
Impaired Long Lived Assets Held Used And Held For Sale Properties [Line Items]
Number Of Properties Accounted For At Fair Value | Property	1
Fair Value Estimated Using Listing Price or Broker Opinion of Value | Industrial | Weighted Average
Impaired Long Lived Assets Held Used And Held For Sale Properties [Line Items]
Weighted Average Price (in dollars per sq ft)	13.79
Fair Value Estimated Using Listing Price or Broker Opinion of Value | Industrial | Measurement Input, Price Per Square Foot
Impaired Long Lived Assets Held Used And Held For Sale Properties [Line Items]
Price per square foot range	13.79
Fair Value Estimated Using Listing Price or Broker Opinion of Value | Industrial | Measurement Input Square Footage
Impaired Long Lived Assets Held Used And Held For Sale Properties [Line Items]
Square Footage | ft²	35,551
Fair Value Estimated Using Listing Price or Broker Opinion of Value | Office
Impaired Long Lived Assets Held Used And Held For Sale Properties [Line Items]
Number Of Properties Accounted For At Fair Value | Property	1	1
Fair Value Estimated Using Listing Price or Broker Opinion of Value | Office | Weighted Average
Impaired Long Lived Assets Held Used And Held For Sale Properties [Line Items]
Weighted Average Price (in dollars per sq ft)	96.39	99.37
Fair Value Estimated Using Listing Price or Broker Opinion of Value | Office | Measurement Input, Price Per Square Foot
Impaired Long Lived Assets Held Used And Held For Sale Properties [Line Items]
Price per square foot range	96.39	99.37
Fair Value Estimated Using Listing Price or Broker Opinion of Value | Office | Measurement Input Square Footage
Impaired Long Lived Assets Held Used And Held For Sale Properties [Line Items]
Square Footage | ft²	4,310	4,310