Organization, Basis of Presentation and Summary of Significant Accounting Policies - Schedule of Operating Partnership's Equity Interest (Details) $ in Millions	6 Months Ended
	Jun. 30, 2021 USD ($)
Fund II and Mervyns II
Variable Interest Entity [Line Items]
Operating Partnership Share of Capital	28.33%
Capital Called	$ 373.4
Unfunded Commitment	$ 11.9
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	$ 448.1
Unfunded Commitment	$ 1.9
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	$ 488.1
Unfunded Commitment	$ 41.9
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	$ 36.9