Commitments and Contingencies - Contractual Obligations (Details) $ in Millions	3 Months Ended
Mar. 31, 2021 USD ($)
Fashion District Philadelphia
Other Commitments [Line Items]
Unaccrued contractual obligation and other commitments	$ 4.8
Percentage of contractual obligation	100.00%
Ownership percentage	50.00%
Construction in Progress
Other Commitments [Line Items]
Unaccrued contractual obligation and other commitments	$ 9.4

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant