Organization, Basis of Presentation and Summary of Significant Accounting Policies - Schedule of Operating Partnership's Equity Interest (Details) - USD ($) $ in Millions	1 Months Ended		9 Months Ended
	Jun. 30, 2020	Apr. 30, 2018	Sep. 30, 2020
Operating Partnership, as General Partner or Managing Member
Variable Interest Entity [Line Items]
Total Distributions		$ 4.3
Fund II and Mervyns II
Variable Interest Entity [Line Items]
Operating Partnership Share of Capital			28.33%
Capital Called			$ 369.6
Unfunded Commitment			$ 15.7
Equity interest held by Operating Partnership			28.33%
Preferred Return			8.00%
Total Distributions			$ 169.8
Fund III
Variable Interest Entity [Line Items]
Operating Partnership Share of Capital			24.54%
Capital Called			$ 440.3
Unfunded Commitment			$ 9.7
Equity interest held by Operating Partnership			24.54%
Preferred Return			6.00%
Total Distributions			$ 568.8
Fund IV
Variable Interest Entity [Line Items]
Operating Partnership Share of Capital			23.12%
Capital Called			$ 457.1
Unfunded Commitment			$ 72.9
Equity interest held by Operating Partnership			23.12%
Preferred Return			6.00%
Total Distributions			$ 193.1
Fund V
Variable Interest Entity [Line Items]
Operating Partnership Share of Capital			20.10%
Capital Called			$ 217.1
Unfunded Commitment			$ 302.9
Equity interest held by Operating Partnership			20.10%
Preferred Return			6.00%
Total Distributions			$ 20.9
Fund II
Variable Interest Entity [Line Items]
Total Distributions		$ 15.0
Fund II | Mervyns II
Variable Interest Entity [Line Items]
Total Distributions	$ 7.5