Bradley Agreement (Details) (USD $) In Thousands, unless otherwise specified	1 Months Ended	3 Months Ended		12 Months Ended
	Apr. 30, 2000	Mar. 31, 2014 item	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Deficiency payments
Deficiency payments:
Balance at the beginning of the year		$ 14,649		$ 14,649
Deficiency payments made		25
Deficiency payments received		(117)
Balance at the end of the year		14,557
Bradley International Airport parking facilities operating agreement
Agreement
Agreement period with the State of Connecticut for operation of parking spaces	25 years
Number of garage parking spaces at Bradley International Airport operated		3,500
Annual minimum guaranteed payment to the State by the trustee				10,815	10,593
Deficiency payments:
Maximum premium percentage on initial deficiency payment		10.00%
Net deficiency payments received (paid)		92	403
Premium income on deficiency payment received from trustee		14
Estimated accrued deficiency payments		0			100
Compensation
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		13,983			13,733
Management fees		0	0
Bradley International Airport parking facilities operating agreement | Low end of the range
Agreement
Annual minimum guaranteed payment to the State by the trustee		8,300
Bradley International Airport parking facilities operating agreement | High end of the range
Agreement
Annual minimum guaranteed payment to the State by the trustee		13,200
Bradley International Airport parking facilities operating agreement | State of Connecticut special facility revenue bonds | Low end of the range
Agreement
Annual principal and interest on revenue bonds		3,600
Bradley International Airport parking facilities operating agreement | State of Connecticut special facility revenue bonds | High end of the range
Agreement
Annual principal and interest on revenue bonds		$ 4,500