Investment in Unconsolidated Entities (Details 2) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011
Loans To SPG-FCM
Interest income from SPG-FCM and Mills loans, net of inter-entity eliminations	$ 2.0	$ 7.4
Base interest rate for loans to SPG-FCM and Mills	LIBOR
Basis points added to base rate for remaining loan to SPG-FCM (as a percent)	2.75%

The number of basis points added to the reference rate to compute the variable interest rate for the related party note outstanding at the balance sheet date.

No definition available.

Name:	simon_NotesReceivableRelatedPartyStatedVariableRate
Namespace Prefix:	simon_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant