Amount, after tax, of accumulated gain (loss) on derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=118930883&loc=d3e637-108580

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- Definition

Fair value of the assets less the liabilities of a derivative or group of derivatives.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=118260190&loc=d3e13433-108611

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- Definition

Fixed interest rate related to the interest rate derivative.

+ References

No definition available.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
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-SubTopic 10
-Section 50
-Paragraph 1A
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- Definition

Fixed interest rate that will be received or paid upon exercise of the interest rate swaption contract.

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- Definition

Fair value as of the balance sheet date of interest rate derivative assets, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as assets.

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Number of interest rate derivative instruments held by the entity at the reporting date.

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-Name Accounting Standards Codification
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Summary of Significant Accounting Policies - Derivative Financial Instruments (Details) € in Millions, $ in Millions	Sep. 30, 2019 EUR (€) DerivativeInstrument	Sep. 30, 2019 USD ($) DerivativeInstrument	Dec. 31, 2018 EUR (€) DerivativeInstrument	Dec. 31, 2018 USD ($) DerivativeInstrument	Sep. 30, 2018 EUR (€)	Sep. 30, 2018 USD ($)
Interest rate swap \| Designated as Hedging Instrument
Derivative Financial Instruments
Number of Instruments \| DerivativeInstrument	0	0	0	0
USD-Euro currency forward contract \| May 15, 2019 \| Net Investment Hedging \| Designated as Hedging Instrument
Derivative Financial Instruments
Notional Amount \| €			€ 50.0
Forward contract net, fair value				$ (0.8)
USD-Euro currency forward contract \| October 2, 2019 \| Net Investment Hedging \| Designated as Hedging Instrument
Derivative Financial Instruments
Notional Amount \| €	€ 375.0
Forward contract net, fair value		$ (6.0)
USD-Euro currency forward contract \| December 18, 2019 \| Net Investment Hedging \| Designated as Hedging Instrument
Derivative Financial Instruments
Notional Amount \| €	100.0
Forward contract net, fair value		1.0
USD-Euro currency forward contract \| December 18, 2019 \| Net Investment Hedging \| Designated as Hedging Instrument
Derivative Financial Instruments
Notional Amount \| €	100.0
Forward contract net, fair value		1.0
USD-Euro currency forward contract \| December 18, 2019 \| Net Investment Hedging \| Designated as Hedging Instrument
Derivative Financial Instruments
Notional Amount \| €	100.0
Forward contract net, fair value		1.0
USD-Euro currency forward contract \| May 15, 2020 \| Net Investment Hedging \| Designated as Hedging Instrument
Derivative Financial Instruments
Notional Amount \| €	50.0		50.0
Forward contract net, fair value		2.7		(1.5)
USD-Euro currency forward contract \| May 14, 2021 \| Net Investment Hedging \| Designated as Hedging Instrument
Derivative Financial Instruments
Notional Amount \| €	€ 50.0		€ 50.0
Forward contract net, fair value		2.4		(2.0)
US denominated cross currency swap \| Net Investment Hedging \| Designated as Hedging Instrument
Derivative Financial Instruments
Notional Amount						$ 150.0
Swapping interest rate					4.38%	4.38%
Euro denominated cross currency swap \| Net Investment Hedging \| Designated as Hedging Instrument
Derivative Financial Instruments
Notional Amount \| €					€ 121.6
Fixed exchange rate					1.37%	1.37%
Euro denominated cross currency swap \| Deferred costs and other assets \| Net Investment Hedging \| Designated as Hedging Instrument
Derivative Financial Instruments
Interest rate derivative asset, fair value		18.7		10.9
Simon Property Group, L.P.
Derivative Financial Instruments
Gross accumulated other comprehensive income related to derivative activities		$ 56.4		$ 37.9