Segment and Geographic Information - Schedule of operating revenues, property and equipment by geographic areas (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Revenues from external customers and long-lived assets [line items]
Operating Revenues	$ 7,985.0	$ 7,101.0	$ 7,140.0
Property and equipment, net	564.1	582.7	589.7
United States [Member]
Revenues from external customers and long-lived assets [line items]
Operating Revenues	5,389.5	4,791.9	4,589.4
Property and equipment, net	443.4	447.9	441.9
The Bahamas [Member]
Revenues from external customers and long-lived assets [line items]
Operating Revenues	1,049.7	904.2	1,041.9
Property and equipment, net	15.7	16.5	17.2
Asia-Pacific [Member]
Revenues from external customers and long-lived assets [line items]
Operating Revenues	661.0	627.7	688.9
Property and equipment, net	81.0	94.3	103.3
Europe, the Middle East and Africa [Member]
Revenues from external customers and long-lived assets [line items]
Operating Revenues	547.8	458.6	435.3
Property and equipment, net	15.3	13.0	15.0
Canada [Member]
Revenues from external customers and long-lived assets [line items]
Operating Revenues	323.3	309.0	344.6
Property and equipment, net	8.1	10.4	11.5
Latin America [Member]
Revenues from external customers and long-lived assets [line items]
Operating Revenues	13.7	9.6	39.9
Property and equipment, net	$ 0.6	$ 0.6	$ 0.8