Represents the maturity periods of the investments held by the entity.

No definition available.

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- Definition

Accumulated appreciation or loss, net of tax, in value of the total of available-for-sale securities at the end of an accounting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14A
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-Section 45
-Paragraph 10A
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=66004124&loc=SL7669646-108580

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Amount, after adjustment, of cost-method investment. Adjustments include, but are not limited to, dividends received in excess of earnings after date of investment that are considered a return of investment and other than temporary impairments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 325
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6872867&loc=d3e40691-111596

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-Name Accounting Standards Codification
-Topic 325
-SubTopic 20
-Section 35
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=29638308&loc=d3e40346-111594

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Period Type:	instant

- Definition

This item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain (loss) of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. Additionally, this item would include any gains (losses) realized during the period from the sale of investments accounted for under the cost method of accounting and losses recognized for other than temporary impairments (OTTI) of the subject investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

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.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
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- Definition

Balance held at close of period in number of shares.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 320
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Balance Type:	na
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- Definition

Total debt and equity financial instruments including: (1) securities held-to-maturity, (2) trading securities, and (3) securities available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.4)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

The cash inflow associated with the sale of equity securities classified as available-for-sale securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Publisher FASB
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-Glossary Investing Activities
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Period Type:	duration

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Name:	us-gaap_InvestmentSecondaryCategorizationAxis=spg_U.S.TreasuryOrGovernmentAndCorporateDebtSecuritiesMember
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Summary of Significant Accounting Policies - Marketable and Non Marketable Securities (Details) - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
	Jun. 24, 2015	Dec. 31, 2016	Dec. 31, 2015
Marketable and Non-Marketable Securities
Net unrealized gains recorded in other comprehensive income (loss)		$ 15,400	$ 12,600
Gain on sale of investment			80,187
Carrying value of investments under the cost method		210,500	181,400
Available for sale securities
Marketable and Non-Marketable Securities
Marketable Securities		$ 156,200	183,800
Number of shares owned	5,710
Proceeds received from the sale of investments	$ 454,000
Gain on sale of investment			$ 80,200
Available for sale securities \| Securities in captive insurance subsidiary portfolio \| Minimum
Marketable and Non-Marketable Securities
Investment maturity period		1 year
Available for sale securities \| Securities in captive insurance subsidiary portfolio \| Maximum
Marketable and Non-Marketable Securities
Investment maturity period		10 years