Derivative Financial Instruments	12 Months Ended
Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	Derivative Financial Instruments The Company’s primary objective in holding derivatives is to reduce the volatility of earnings and cash flows associated with changes in interest rates. The Company measures its derivative financial instruments at fair value. Australia - Fullham The Company’s Australian subsidiary was a party to an interest rate swap agreement to fix the interest rate on the variable rate non-recourse debt to 9.7%. The Company has determined the swap's payment and expiration dates, and call provisions that coincided with the terms of the non-recourse debt, to be an effective cash flow hedge. Accordingly, the Company recorded the change in the value of the interest rate swap in accumulated other comprehensive income, net of applicable income taxes. Total unrealized gains recorded in other comprehensive income, net of tax, related to this cash flow hedge were not significant for the years ended December 31, 2017 or 2016. During 2017, the associated non-recourse debt was paid off and the interest rate swap is no longer in existence as of December 31, 2017. Australia - Ravenhall In September 2014, the Company’s Australian subsidiary entered into interest rate swap agreements to fix the interest rate on its variable rate non-recourse debt related to a prison project in Ravenhall, a locality near Melbourne, Australia to 3.3% during the design and construction phase and 4.2% during the project’s operating phase. Refer to Note 7 - Contract Receivable. The swaps’ notional amounts during the design and construction phase coincided with scheduled construction draw commitments throughout the project. The design and construction phase of the project was completed during November 2017 and the related interest rate swap agreements expired. At December 31, 2017, the swaps related to the operating phase had a notional value of approximately AUD 466.3 million, or $364.0 million. At the onset, the Company had determined that the swaps have payment, expiration dates and provisions that coincide with the terms of the non-recourse debt and the critical terms of the swap agreements and scheduled construction draw commitments were the same and were therefore considered to be effective cash flow hedges. During 2017 and 2016, certain of the critical terms of the swap agreements related to the design and construction phase no longer coincided with the scheduled construction draw commitments. However, the swaps were still considered to be highly effective and the measurement of any ineffectiveness was not significant during the year ended December 31, 2017 or 2016. Accordingly, the Company records the change in the fair value of the interest rate swaps in accumulated other comprehensive income, net of applicable income taxes. Total unrealized gains recorded in other comprehensive income, net of tax, related to this cash flow hedge were approximately $4.0 million during the year ended December 31, 2017. The total fair value of the swap liability as of December 31, 2017 was $14.0 million and is recorded as a component of Other Non-Current liabilities within the accompanying consolidated balance sheet. There was no material ineffectiveness for the periods presented. The Company does not expect to enter into any transactions during the next twelve months which would result in the reclassification into earnings or losses associated with these swaps currently reported in accumulated other comprehensive income (loss). Additionally, upon completion and commercial acceptance of the prison project in November 2017, the State, in accordance with the prison contract, made a lump sum payment of AUD 310 million, or $242.0 million, based on exchange rates at December 31, 2017, towards a portion of the outstanding balance which was used to pay down the principal of the non-recourse debt. The Company’s Australian subsidiary had also entered into interest rate cap agreements in September 2014 giving the Company the option to cap the interest rate on its variable non-recourse debt related to the project in the event that the completion of the prison project was delayed which could have delayed the State’s payment. These instruments did not meet the requirements for hedge accounting, and therefore, changes in fair value of the interest rate caps were recorded in earnings which was not significant during 2017, 2016 or 2015. As the project was not delayed and the State's payment was received according to schedule, these interest rate cap assets were not put into effect.

Derivative Financial Instruments

The Company’s primary objective in holding derivatives is to reduce the volatility of earnings and cash flows associated with changes in interest rates. The Company measures its derivative financial instruments at fair value.

Australia - Fullham

The Company’s Australian subsidiary was a party to an interest rate swap agreement to fix the interest rate on the variable rate non-recourse debt to 9.7%. The Company has determined the swap's payment and expiration dates, and call provisions that coincided with the terms of the non-recourse debt, to be an effective cash flow hedge. Accordingly, the Company recorded the change in the value of the interest rate swap in accumulated other comprehensive income, net of applicable income taxes. Total unrealized gains recorded in other comprehensive income, net of tax, related to this cash flow hedge were not significant for the years ended December 31, 2017 or 2016. During 2017, the associated non-recourse debt was paid off and the interest rate swap is no longer in existence as of December 31, 2017.

Australia - Ravenhall

In September 2014, the Company’s Australian subsidiary entered into interest rate swap agreements to fix the interest rate on its variable rate non-recourse debt related to a prison project in Ravenhall, a locality near Melbourne, Australia to 3.3% during the design and construction phase and 4.2% during the project’s operating phase. Refer to Note 7 - Contract Receivable. The swaps’ notional amounts during the design and construction phase coincided with scheduled construction draw commitments throughout the project. The design and construction phase of the project was completed during November 2017 and the related interest rate swap agreements expired. At December 31, 2017, the swaps related to the operating phase had a notional value of approximately AUD 466.3 million, or $364.0 million. At the onset, the Company had determined that the swaps have payment, expiration dates and provisions that coincide with the terms of the non-recourse debt and the critical terms of the swap agreements and scheduled construction draw commitments were the same and were therefore considered to be effective cash flow hedges. During 2017 and 2016, certain of the critical terms of the swap agreements related to the design and construction phase no longer coincided with the scheduled construction draw commitments. However, the swaps were still considered to be highly effective and the measurement of any ineffectiveness was not significant during the year ended December 31, 2017 or 2016. Accordingly, the Company records the change in the fair value of the interest rate swaps in accumulated other comprehensive income, net of applicable income taxes. Total unrealized gains recorded in other comprehensive income, net of tax, related to this cash flow hedge were approximately $4.0 million during the year ended December 31, 2017. The total fair value of the swap liability as of December 31, 2017 was $14.0 million and is recorded as a component of Other Non-Current liabilities within the accompanying consolidated balance sheet. There was no material ineffectiveness for the periods presented. The Company does not expect to enter into any transactions during the next twelve months which would result in the reclassification into earnings or losses associated with these swaps currently reported in accumulated other comprehensive income (loss).

Additionally, upon completion and commercial acceptance of the prison project in November 2017, the State, in accordance with the prison contract, made a lump sum payment of AUD 310 million, or $242.0 million, based on exchange rates at December 31, 2017, towards a portion of the outstanding balance which was used to pay down the principal of the non-recourse debt. The Company’s Australian subsidiary had also entered into interest rate cap agreements in September 2014 giving the Company the option to cap the interest rate on its variable non-recourse debt related to the project in the event that the completion of the prison project was delayed which could have delayed the State’s payment. These instruments did not meet the requirements for hedge accounting, and therefore, changes in fair value of the interest rate caps were recorded in earnings which was not significant during 2017, 2016 or 2015. As the project was not delayed and the State's payment was received according to schedule, these interest rate cap assets were not put into effect.