Bradley Agreement - Additional Information (Details)	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	May 31, 2019	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) parking_space	Sep. 30, 2018 USD ($)	Dec. 31, 2024 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2002 USD ($)	Dec. 31, 2025 USD ($)
Bradley International Airport parking facilities operating agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Agreement period for operation of parking spaces				25 years
Number of garage parking spaces at Bradley International Airport operated | parking_space				3,500
Annual minimum guaranteed payment to the State by the trustee								$ 11,800,000
Maximum premium percentage on initial deficiency payment (not more than)				10.00%
Estimated accrued deficiency payments		$ 0		$ 0				0
Management fee apportioned to the entity (as a percent)				60.00%
Management fee apportioned to an un-affiliated entity (as a percent)				40.00%
Unrecognized cumulative management fees		19,500,000		$ 19,500,000				$ 18,700,000
Management fees		$ 0	$ 0	$ 0	$ 0
Minimum | Bradley International Airport parking facilities operating agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Annual minimum guaranteed payment to the State by the trustee									$ 8,300,000
State of Connecticut special facility revenue bonds | Minimum | Bradley International Airport parking facilities operating agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Annual principal and interest on revenue bonds									$ 3,600,000
Forecast | Bradley International Airport parking facilities operating agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Annual minimum guaranteed payment to the State by the trustee							$ 12,000,000.0
Forecast | Maximum | Bradley International Airport parking facilities operating agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Annual minimum guaranteed payment to the State by the trustee						$ 13,200,000
Forecast | State of Connecticut special facility revenue bonds | Maximum | Bradley International Airport parking facilities operating agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Annual principal and interest on revenue bonds										$ 4,500,000
Interest rate contract
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Derivative, Term of Contract	3 years