Debt (6.50% Exchangeable Senior Notes) (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2021 USD ($) $ / shares	Dec. 31, 2020 Instrument $ / shares	Feb. 24, 2021 USD ($)	Sep. 30, 2020
Debt Instrument [Line Items]
Common stock, par value (in dollars per share) | $ / shares	$ 0.01	$ 0.01
Number of convertible instruments | Instrument		0
6.50% Exchangeable Senior Notes due 2026
Debt Instrument [Line Items]
Debt instrument, face amount			$ 230,000,000
Stated interest rate	6.50%
5.875% Senior Notes due 2024
Debt Instrument [Line Items]
Stated interest rate	5.875%	5.875%
Convertible Notes | 6.50% Exchangeable Senior Notes due 2026
Debt Instrument [Line Items]
Debt instrument, face amount			$ 230,000,000
Stated interest rate	6.50%	6.50%	6.50%
Debt instrument, maturity date	Feb. 23, 2026
Debt instrument, payment terms	Interest on the notes is payable semi-annually in arrears on March 1 and September 1 of each year, beginning on September 1, 2021.
Debt instrument, commencement date of first required payment	Sep. 01, 2021
Debt instrument, frequency of payment	semi-annually
Debt exchange, description	Subject to certain restrictions on share ownership and transfer, holders may exchange the notes at their option prior to the close of business on the business day immediately preceding November 25, 2025, but only under the following circumstances: (1) during the five consecutive business day period after any five consecutive trading day period, or the measurement period, in which the trading price per $1,000 principal amount of notes for each trading day of such measurement period was less than 98% of the product of the last reported sale price of the Company’s common stock and the exchange rate for the notes on each such trading day; or (2) upon the occurrence of certain specified corporate events. On or after November 25, 2025, until the close of business on the second scheduled trading day immediately preceding the maturity date of the notes, holders may exchange their notes at any time, regardless of the foregoing circumstances. Upon exchange of a note, GEO will pay or deliver, as the case may be, cash or a combination of cash and shares of the Company’s common stock. As of September 30, 2021, conditions had not been met to exchange the notes.
Debt instrument, initial conversion rate per $1,000 principal amount	108.4011
Debt instrument, initial conversion price | $ / shares	$ 9.225
Percentage of principal amount of notes to be purchased	100.00%
Costs incurred in issuance, including initial purchasers discount	$ 9,600,000
Convertible Notes | 6.50% Exchangeable Senior Notes due 2026 | Maximum
Debt Instrument [Line Items]
Percentage of trading price per $1,000 principal amount against last reported sale price and exchange rate of notes	98.00%
Convertible Notes | 6.50% Exchangeable Senior Notes due 2026 | Over=Allotment Option
Debt Instrument [Line Items]
Debt instrument, face amount			$ 30,000,000
Senior Notes | 5.875% Senior Notes due 2024
Debt Instrument [Line Items]
Stated interest rate	5.875%	5.875%		5.875%
Redemption of outstanding amount	$ 194,000,000.0
Write off of deferred loan costs to loss on extinguishment of debt	$ 700,000