Schedule I - Condensed Financial Information of Registrant - Statements of Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Lease revenue									$ 1,127.1	$ 1,130.1	$ 1,086.6
Other revenue									91.9	84.8	78.1
Total Revenues	$ 362.1	$ 362.9	$ 358.9	$ 334.4	$ 378.7	$ 386.2	$ 365.3	$ 319.7	1,418.3	1,449.9	1,451.0
Maintenance expense									332.3	326.1	337.0
Depreciation									297.2	290.5	273.5
Operating lease expense									73.5	87.2	108.7
Other operating expense									43.8	38.4	28.9
Selling, general and administrative									174.7	192.4	189.2
Total Expenses									1,051.0	1,090.5	1,135.1
Net gain on asset dispositions									98.0	79.2	87.2
Interest expense, net									(148.1)	(155.1)	(158.4)
Other (expense) income									(11.8)	(13.2)	(13.5)
Income before Income Taxes and Share of Affiliates’ Earnings									305.4	270.3	231.2
Income tax benefit									(95.7)	(110.9)	(75.7)
Share of affiliates' earnings (net of tax)									47.4	45.9	49.5
Net Income	$ 30.9	$ 95.7	$ 61.2	$ 69.3	$ 58.2	$ 39.5	$ 45.4	$ 62.2	257.1	205.3	205.0
Foreign currency translation adjustments									(26.0)	(55.8)	(79.1)
Unrealized gain (loss) on securities									0.3	(0.6)	(0.1)
Unrealized gain (loss) on derivative instruments									0.6	(1.8)	3.0
Post-retirement benefit plans									12.8	7.8	(29.5)
Other comprehensive income (loss)									(12.3)	(50.4)	(105.7)
Comprehensive Income									244.8	154.9	99.3
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Lease revenue									720.8	718.3	669.7
Other revenue									76.3	66.7	60.2
Total Revenues									797.1	785.0	729.9
Maintenance expense									240.8	233.6	227.6
Depreciation									176.8	164.8	147.7
Operating lease expense									59.0	61.7	83.0
Other operating expense									31.5	25.4	17.1
Selling, general and administrative									133.5	149.2	139.7
Total Expenses									641.6	634.7	615.1
Net gain on asset dispositions									131.2	48.0	67.9
Interest expense, net									(59.4)	(68.7)	(66.7)
Other (expense) income									(6.5)	0.0	2.5
Income before Income Taxes and Share of Affiliates’ Earnings									220.8	129.6	118.5
Income tax benefit									(103.3)	(62.4)	(41.7)
Share of affiliates' earnings (net of tax)									139.6	138.1	128.2
Net Income									257.1	205.3	205.0
Foreign currency translation adjustments									(26.0)	(55.8)	(79.1)
Unrealized gain (loss) on securities									0.3	(0.6)	(0.1)
Unrealized gain (loss) on derivative instruments									0.6	(1.8)	3.0
Post-retirement benefit plans									12.8	7.8	(29.5)
Other comprehensive income (loss)									(12.3)	(50.4)	(105.7)
Comprehensive Income									$ 244.8	$ 154.9	$ 99.3