Commitments and Contingencies - Insurance (Details) $ in Billions	12 Months Ended
Dec. 31, 2020 USD ($)
Insurance
Insurance coverage, acts of terrorism	$ 1

The amount of coverage per occurrence against acts of terrorism maintained by the entity.

No definition available.

Name:	spg_InsuranceCoverageAllActsOfTerrorism
Namespace Prefix:	spg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration