Investment in Unconsolidated Entities (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2012
Loan To SPG-FCM
Interest income from SPG-FCM and Mills loans, net of inter-entity eliminations	$ 2.0

Interest income earned on notes receivable from related parties during the reporting period, net of inter-entity eliminations.

No definition available.

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Namespace Prefix:	simon_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration