Schedule I - Condensed Financial Information of Registrant - Statements of Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Financial Statements, Captions [Line Items]
Lease revenue									$ 1,086.6	$ 975.2	$ 917.0
Other revenue									78.1	70.7	60.7
Total Revenues	401.4	397.2	365.8	286.6	356.6	353.2	338.9	272.3	1,451.0	1,321.0	1,243.2
Maintenance expense									337.0	294.0	269.7
Depreciation									273.5	255.0	237.4
Operating lease expense									108.7	129.4	130.2
Other operating expense									28.9	26.1	24.2
Selling, general and administrative									189.2	178.3	160.2
Total Expenses									1,135.1	1,072.6	1,004.1
Net gain on asset dispositions									87.2	85.6	79.5
Interest expense, net									(158.4)	(166.6)	(166.6)
Other (expense) income									(13.5)	(8.4)	(8.2)
Income before Income Taxes and Share of Affiliates’ Earnings									231.2	159.0	143.8
Income tax benefit									(75.7)	(65.5)	(26.1)
Share of affiliates' earnings (net of tax)									49.5	75.8	19.6
Net Income	58.5	51.3	53.1	42.1	53.3	53.8	35.1	27.1	205.0	169.3	137.3
Foreign currency translation adjustments									(79.1)	25.8	25.0
Unrealized gain (loss) on securities									(0.1)	0.8	0.2
Unrealized gain (loss) on derivative instruments									3.0	22.4	11.7
Post-retirement benefit plans									(29.5)	52.9	(12.4)
Other comprehensive income (loss)									(105.7)	101.9	24.5
Comprehensive Income									99.3	271.2	161.8
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Lease revenue									669.7	543.0	504.5
Other revenue									60.2	51.3	43.5
Total Revenues									729.9	594.3	548.0
Maintenance expense									227.6	176.5	154.8
Depreciation									147.7	131.1	122.2
Operating lease expense									83.0	89.5	91.6
Other operating expense									17.1	12.7	12.0
Selling, general and administrative									139.7	131.1	118.4
Total Expenses									615.1	540.9	499.0
Net gain on asset dispositions									67.9	68.6	59.4
Interest expense, net									(66.7)	(63.7)	(65.4)
Other (expense) income									2.5	(7.0)	(4.4)
Income before Income Taxes and Share of Affiliates’ Earnings									118.5	51.3	38.6
Income tax benefit									(41.7)	(10.7)	1.0
Share of affiliates' earnings (net of tax)									128.2	128.7	97.7
Net Income									205.0	169.3	137.3
Foreign currency translation adjustments									(79.1)	25.8	25.0
Unrealized gain (loss) on securities									(0.1)	0.8	0.2
Unrealized gain (loss) on derivative instruments									3.0	22.4	11.7
Post-retirement benefit plans									(29.5)	52.9	(12.4)
Other comprehensive income (loss)									(105.7)	101.9	24.5
Comprehensive Income									$ 99.3	$ 271.2	$ 161.8