Fair Value Measurements and the Fair Value Option - Schedule of Significant Inputs (Details)	Mar. 31, 2020
Measurement Input, Cap Rate [Member] | Multifamily [Member] | Minimum [Member] | Valuation, Income and Market Approach [Member] | Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement inputs	0.0375
Measurement Input, Cap Rate [Member] | Multifamily [Member] | Maximum [Member] | Valuation, Income and Market Approach [Member] | Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement inputs	0.0500
Measurement Input, Cap Rate [Member] | Office [Member] | Minimum [Member] | Valuation, Income and Market Approach [Member] | Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement inputs	0.0400
Measurement Input, Cap Rate [Member] | Office [Member] | Maximum [Member] | Valuation, Income and Market Approach [Member] | Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement inputs	0.0750
Measurement Input, Cap Rate [Member] | Retail [Member] | Minimum [Member] | Valuation, Income and Market Approach [Member] | Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement inputs	0.0650
Measurement Input, Cap Rate [Member] | Retail [Member] | Maximum [Member] | Valuation, Income and Market Approach [Member] | Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement inputs	0.0875
Measurement Input, Cap Rate [Member] | Hotel [Member] | Minimum [Member] | Valuation, Income and Market Approach [Member] | Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement inputs	0.0600
Measurement Input, Cap Rate [Member] | Hotel [Member] | Maximum [Member] | Valuation, Income and Market Approach [Member] | Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement inputs	0.0600
Measurement Input, Discount Rate [Member] | Multifamily [Member] | Minimum [Member] | Valuation, Income and Market Approach [Member] | Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement inputs	0.0625
Measurement Input, Discount Rate [Member] | Multifamily [Member] | Maximum [Member] | Valuation, Income and Market Approach [Member] | Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement inputs	0.0800
Measurement Input, Discount Rate [Member] | Office [Member] | Minimum [Member] | Valuation, Income and Market Approach [Member] | Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement inputs	0.0500
Measurement Input, Discount Rate [Member] | Office [Member] | Maximum [Member] | Valuation, Income and Market Approach [Member] | Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement inputs	0.0900
Measurement Input, Discount Rate [Member] | Retail [Member] | Minimum [Member] | Valuation, Income and Market Approach [Member] | Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement inputs	0.0800
Measurement Input, Discount Rate [Member] | Retail [Member] | Maximum [Member] | Valuation, Income and Market Approach [Member] | Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement inputs	0.1175
Measurement Input, Discount Rate [Member] | Hotel [Member] | Minimum [Member] | Valuation, Income and Market Approach [Member] | Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement inputs	0.0750
Measurement Input, Discount Rate [Member] | Hotel [Member] | Maximum [Member] | Valuation, Income and Market Approach [Member] | Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement inputs	0.0825
Measurement Input, Discount Rate [Member] | Residential [Member] | Minimum [Member] | Valuation, Income and Market Approach [Member] | Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement inputs	0.1200
Measurement Input, Discount Rate [Member] | Residential [Member] | Maximum [Member] | Valuation, Income and Market Approach [Member] | Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement inputs	0.1200
Measurement Input, Credit Spread [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement inputs	0.0130
Measurement Input, Credit Spread [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement inputs	0.0462