Property and Equipment (Narrative) (Details) (Flight Equipment [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Leases, Future Minimum Payments Receivable [Abstract]
Minimum future lease payments, Due within next 12 months	$ 62.8
Minimum future lease payments, Due within next 2 years	53.5
Minimum future lease payments, Due within next 3 years	34.0
Minimum future lease payments, Due within next 4 years	17.6
Minimum future lease payments, Due within next 5 years	8.7
Proceeds from sale of flight equipment	3.6	1.5	5.8
CAM [Member]
Property, Plant and Equipment [Line Items]
Leased aircraft, carrying value	289.5	250.9
Boeing 727 and DC-8 aircraft and flight equipment [Member]
Operating Leases, Future Minimum Payments Receivable [Abstract]
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment	$ 0.7	$ 3.0