Significant Accounting Policies (Details 2) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
Sep. 30, 2012	Dec. 31, 2012 Item
Loans Held for Investment
Number of mortgage and mezzanine loans secured by real estate repaid during the year		3
Interest income on loans held for investment	$ 6.8

The number of loans on real estate, both mortgage and mezzanine, that are held for investment.

No definition available.

Name:	spg_MortgageLoansOnRealEstateHeldForInvestmentNumberOfLoans
Namespace Prefix:	spg_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration