Equity - Shares or Units Activity (Details) $ / shares in Units, $ in Millions					3 Months Ended					9 Months Ended
	Oct. 23, 2020 $ / shares	Sep. 29, 2020 $ / shares	Feb. 11, 2019 USD ($)	Feb. 13, 2017 USD ($)	Sep. 30, 2020 $ / shares shares	Mar. 31, 2020 shares	Sep. 30, 2019 $ / shares shares	Jun. 30, 2019 shares	Mar. 31, 2019 shares	Sep. 30, 2020 USD ($) item $ / shares shares	Sep. 30, 2019 $ / shares shares
Equity
Redemption of units					586	116,072	27,214		774
Exchange of limited partner units, (in shares)					61,968	132,946			24,000
Common stock authorized for repurchase | $			$ 2,000.0	$ 2,000.0
Period common stock is authorized to repurchase			2 years
Stock repurchase program, extension period				2 years
Shares repurchased (in shares)						1,245,654	1,154,117	1,046,580	46,377	1,245,654	2,247,074
Average share price repurchased (in dollars per share) | $ / shares										$ 122.50	$ 160.11
Common stock dividends paid (in dollars per share) | $ / shares					$ 1.30		$ 2.10			$ 3.40	$ 6.20
Dividends declared per common share (in dollars per share) | $ / shares	$ 1.30	$ 1.30
Limited Partners
Equity
Exchange of limited partner units, (in shares)										194,914
Number of limited partners who received common stock | item										6
2017 Share Repurchase Program
Equity
Shares repurchased (in shares)											46,377
Average share price repurchased (in dollars per share) | $ / shares											$ 164.49
Simon Property Group, L.P.
Equity
Redemption of units					586	116,072	27,214		774
Distributions paid per unit (in dollars per unit) | $ / shares					$ 1.30		$ 2.10			$ 3.40	$ 6.20
Simon Property Group, L.P. | Limited Partners
Equity
Redemption of units										116,658
Number of limited partners who received common stock | item										4
Value of units redeemed | $										$ 16.1