Orion Office REIT Inc. Quarterly report pursuant to Section 13 or 15(d)

VEREIT Office Assets, Real Estate Investments and Related Intangibles - Impairments Narrative (Details) - VEREIT Office Assets $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($) property	Sep. 30, 2020 USD ($) property	Sep. 30, 2021 USD ($) property	Sep. 30, 2020 USD ($) property
Real Estate Properties [Line Items]
Number of impaired properties \| property	3	1	4	1
Impairment of real estate \| $	$ 6.4	$ 0.2	$ 28.1	$ 0.2
Discount Rate \| Assets impaired during the three months ended September 30, 2021 \| Weighted Average
Real Estate Properties [Line Items]
Alternative investment, measurement input	0.097		0.097
Discount Rate \| Assets impaired during the nine months ended September 30, 2021 \| Weighted Average
Real Estate Properties [Line Items]
Alternative investment, measurement input	0.090		0.090
Capitalization Rate \| Assets impaired during the three months ended September 30, 2021 \| Weighted Average
Real Estate Properties [Line Items]
Alternative investment, measurement input	0.092		0.092
Capitalization Rate \| Assets impaired during the nine months ended September 30, 2021 \| Weighted Average
Real Estate Properties [Line Items]
Alternative investment, measurement input	0.085		0.085