Investments in Real Estate - Estimated Impact of Amortization of Lease Intangibles (Details) $ in Thousands	Sep. 30, 2021 USD ($)
Net decrease to rental revenue
2021	$ (9,932)
2022	(39,158)
2023	(37,857)
2024	(36,247)
2025	(36,604)
Thereafter	(210,612)
Totals	(370,410)
Increase to amortization expense
2021	48,623
2022	182,918
2023	165,335
2024	149,595
2025	135,666
Thereafter	761,786
Totals	$ 1,443,923

Finite-Lived Intangible Assets, Amortization Expense After Year Four

No definition available.

Name:	o_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFour
Namespace Prefix:	o_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the amount of increase (decrease) in amortization expense expected to be recognized for assets, lacking physical substance with a finite life.

+ References

No definition available.

+ Details

Name:	o_FiniteLivedIntangibleAssetsAmortizationExpenseIncreaseDecrease
Namespace Prefix:	o_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	o_FiniteLivedIntangibleAssetsAmortizationExpenseIncreaseDecreaseAbstract
Namespace Prefix:	o_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the amount of increase (decrease) in rental income expected to be recognized from assets, lacking physical substance with a finite life.

+ References

No definition available.

+ Details

Name:	o_FiniteLivedIntangibleAssetsRentalIncomeIncreaseDecrease
Namespace Prefix:	o_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	o_FiniteLivedIntangibleAssetsRentalIncomeIncreaseDecreaseAbstract
Namespace Prefix:	o_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Finite Lived Intangible Assets Rental Income Increase (Decrease) After Year Four

+ References

No definition available.

+ Details

Name:	o_FiniteLivedIntangibleAssetsRentalIncomeIncreaseDecreaseAfterYearFour
Namespace Prefix:	o_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the amount of increase (decrease) in rental income expected to be recognized in the remainder of the fifth fiscal year following the latest fiscal year from assets, lacking physical substance with a finite life.

+ References

No definition available.

+ Details

Name:	o_FiniteLivedIntangibleAssetsRentalIncomeIncreaseDecreaseRemainderOfFiscalYear
Namespace Prefix:	o_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the amount of increase (decrease) in rental income expected to be recognized during the fourth fiscal year following the latest fiscal year from assets, lacking physical substance with a finite life.

+ References

No definition available.

+ Details

Name:	o_FiniteLivedIntangibleAssetsRentalIncomeIncreaseDecreaseYearFour
Namespace Prefix:	o_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Finite Lived Intangible Assets Rental Income Increase (Decrease) Year One

+ References

No definition available.

+ Details

Name:	o_FiniteLivedIntangibleAssetsRentalIncomeIncreaseDecreaseYearOne
Namespace Prefix:	o_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the amount of increase (decrease) in rental income expected to be recognized during the third fiscal year following the latest fiscal year from assets, lacking physical substance with a finite life.

+ References

No definition available.

+ Details

Name:	o_FiniteLivedIntangibleAssetsRentalIncomeIncreaseDecreaseYearThree
Namespace Prefix:	o_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the amount of increase (decrease) in rental income expected to be recognized during the second fiscal year following the latest fiscal year from assets, lacking physical substance with a finite life.

+ References

No definition available.

+ Details

Name:	o_FiniteLivedIntangibleAssetsRentalIncomeIncreaseDecreaseYearTwo
Namespace Prefix:	o_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in remainder of current fiscal year.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant