Financial Statements for Guarantors of the Senior Notes - Statement of Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2017		Sep. 30, 2016	Sep. 30, 2017		Sep. 30, 2016
Operating activities:
Net income	$ 67.9		$ 89.6	$ 173.6		$ 290.5
Equity in earnings of subsidiaries, net of taxes	0.0		0.0	0.0		0.0
Other				314.6		501.6
Net cash provided (required) by operating activities				488.2		792.1
Investing activities:
(Increase) decrease in short-term marketable securities				84.7		(199.8)
Proceeds from dispositions of property and other assets				8.1		8.9
Proceeds from railcar lease fleet sales owned more than one year				160.3		37.7
Capital expenditures – leasing				(360.4)		(555.2)
Capital expenditures – manufacturing and other				(61.9)		(101.1)
Acquisitions, net of cash acquired	(42.2)		0.0	(47.5)		0.0
(Increase) decrease in investment in partially-owned subsidiaries				0.0		0.0
Other				(0.3)		4.0
Net cash provided (required) by investing activities				(217.0)		(805.5)
Financing activities:
Excess tax benefits from stock-based compensation				0.0		0.8
Payments to retire debt				(334.9)		(106.0)
Proceeds from issuance of debt				534.1		0.0
(Increase) decrease in restricted cash				1.9		11.9
Shares repurchased				(52.4)		(34.7)
Dividends paid to common shareholders				(53.0)		(50.0)
Purchase of shares to satisfy employee tax on vested stock				(14.1)		(16.4)
Distributions to noncontrolling interest				(41.4)		(18.4)
Distributions to controlling interest in partially-owned subsidiaries				0.0		0.0
Change in intercompany financing between entities				0.0		0.0
Other				(0.1)		(2.0)
Net cash provided (required) by financing activities				40.1		(214.8)
Net decrease in cash and cash equivalents				311.3		(228.2)
Cash and cash equivalents at beginning of period				563.4		786.0
Cash and cash equivalents at end of period	874.7	[1]	557.8	874.7	[1]	557.8
Reportable legal entities | Parent
Operating activities:
Net income	66.9		84.2	164.0		276.0
Equity in earnings of subsidiaries, net of taxes	(111.7)		(114.8)	(274.1)		(342.7)
Other				28.5		157.4
Net cash provided (required) by operating activities				(81.6)		90.7
Investing activities:
(Increase) decrease in short-term marketable securities				84.7		(199.8)
Proceeds from dispositions of property and other assets				0.0		0.0
Proceeds from railcar lease fleet sales owned more than one year				0.0		0.0
Capital expenditures – leasing				0.0		0.0
Capital expenditures – manufacturing and other				(5.9)		(12.9)
Acquisitions, net of cash acquired				0.0		0.0
(Increase) decrease in investment in partially-owned subsidiaries				0.0		0.0
Other				0.0		0.0
Net cash provided (required) by investing activities				78.8		(212.7)
Financing activities:
Excess tax benefits from stock-based compensation				0.0		0.8
Payments to retire debt				0.0		0.0
Proceeds from issuance of debt				0.0		0.0
(Increase) decrease in restricted cash				0.0		0.0
Shares repurchased				(52.4)		(34.7)
Dividends paid to common shareholders				(53.0)		(50.0)
Purchase of shares to satisfy employee tax on vested stock				(14.1)		(16.4)
Distributions to noncontrolling interest				0.0		0.0
Distributions to controlling interest in partially-owned subsidiaries				0.0		0.0
Change in intercompany financing between entities				437.4		(22.4)
Other				0.0		0.0
Net cash provided (required) by financing activities				317.9		(122.7)
Net decrease in cash and cash equivalents				315.1		(244.7)
Cash and cash equivalents at beginning of period				537.9		768.3
Cash and cash equivalents at end of period	853.0		523.6	853.0		523.6
Reportable legal entities | Combined Guarantor Subsidiaries
Operating activities:
Net income	85.1		110.7	215.6		309.1
Equity in earnings of subsidiaries, net of taxes	(17.5)		(33.9)	(60.6)		(76.5)
Other				134.9		207.4
Net cash provided (required) by operating activities				289.9		440.0
Investing activities:
(Increase) decrease in short-term marketable securities				0.0		0.0
Proceeds from dispositions of property and other assets				1.2		2.2
Proceeds from railcar lease fleet sales owned more than one year				515.8		27.3
Capital expenditures – leasing				(349.2)		(553.6)
Capital expenditures – manufacturing and other				(12.3)		(10.7)
Acquisitions, net of cash acquired				0.0		0.0
(Increase) decrease in investment in partially-owned subsidiaries				30.0		11.7
Other				0.0		0.0
Net cash provided (required) by investing activities				185.5		(523.1)
Financing activities:
Excess tax benefits from stock-based compensation				0.0		0.0
Payments to retire debt				(2.7)		(2.5)
Proceeds from issuance of debt				0.0		0.0
(Increase) decrease in restricted cash				0.0		0.2
Shares repurchased				0.0		0.0
Dividends paid to common shareholders				0.0		0.0
Purchase of shares to satisfy employee tax on vested stock				0.0		0.0
Distributions to noncontrolling interest				0.0		0.0
Distributions to controlling interest in partially-owned subsidiaries				0.0		0.0
Change in intercompany financing between entities				(471.8)		87.6
Other				0.0		0.0
Net cash provided (required) by financing activities				(474.5)		85.3
Net decrease in cash and cash equivalents				0.9		2.2
Cash and cash equivalents at beginning of period				5.2		1.7
Cash and cash equivalents at end of period	6.1		3.9	6.1		3.9
Reportable legal entities | Combined Non-Guarantor Subsidiaries
Operating activities:
Net income	37.0		38.8	95.2		113.9
Equity in earnings of subsidiaries, net of taxes	0.0		0.0	0.0		0.0
Other				165.7		158.1
Net cash provided (required) by operating activities				260.9		272.0
Investing activities:
(Increase) decrease in short-term marketable securities				0.0		0.0
Proceeds from dispositions of property and other assets				6.9		6.7
Proceeds from railcar lease fleet sales owned more than one year				8.4		10.4
Capital expenditures – leasing				(375.1)		(1.6)
Capital expenditures – manufacturing and other				(43.7)		(77.5)
Acquisitions, net of cash acquired				(47.5)		0.0
(Increase) decrease in investment in partially-owned subsidiaries				0.0		0.0
Other				(0.3)		4.0
Net cash provided (required) by investing activities				(451.3)		(58.0)
Financing activities:
Excess tax benefits from stock-based compensation				0.0		0.0
Payments to retire debt				(332.2)		(103.5)
Proceeds from issuance of debt				534.1		0.0
(Increase) decrease in restricted cash				26.7		10.6
Shares repurchased				0.0		0.0
Dividends paid to common shareholders				0.0		0.0
Purchase of shares to satisfy employee tax on vested stock				0.0		0.0
Distributions to noncontrolling interest				(41.4)		(18.4)
Distributions to controlling interest in partially-owned subsidiaries				(30.0)		(11.7)
Change in intercompany financing between entities				53.5		(75.8)
Other				(0.1)		(2.0)
Net cash provided (required) by financing activities				210.6		(200.8)
Net decrease in cash and cash equivalents				20.2		13.2
Cash and cash equivalents at beginning of period				51.3		51.1
Cash and cash equivalents at end of period	71.5		64.3	71.5		64.3
Eliminations
Operating activities:
Net income	(121.1)		(144.1)	(301.2)		(408.5)
Equity in earnings of subsidiaries, net of taxes	129.2		148.7	334.7		419.2
Other				(14.5)		(21.3)
Net cash provided (required) by operating activities				19.0		(10.6)
Investing activities:
(Increase) decrease in short-term marketable securities				0.0		0.0
Proceeds from dispositions of property and other assets				0.0		0.0
Proceeds from railcar lease fleet sales owned more than one year				(363.9)		0.0
Capital expenditures – leasing				363.9		0.0
Capital expenditures – manufacturing and other				0.0		0.0
Acquisitions, net of cash acquired				0.0		0.0
(Increase) decrease in investment in partially-owned subsidiaries				(30.0)		(11.7)
Other				0.0		0.0
Net cash provided (required) by investing activities				(30.0)		(11.7)
Financing activities:
Excess tax benefits from stock-based compensation				0.0		0.0
Payments to retire debt				0.0		0.0
Proceeds from issuance of debt				0.0		0.0
(Increase) decrease in restricted cash				(24.8)		1.1
Shares repurchased				0.0		0.0
Dividends paid to common shareholders				0.0		0.0
Purchase of shares to satisfy employee tax on vested stock				0.0		0.0
Distributions to noncontrolling interest				0.0		0.0
Distributions to controlling interest in partially-owned subsidiaries				30.0		11.7
Change in intercompany financing between entities				(19.1)		10.6
Other				0.0		0.0
Net cash provided (required) by financing activities				(13.9)		23.4
Net decrease in cash and cash equivalents				(24.9)		1.1
Cash and cash equivalents at beginning of period				(31.0)		(35.1)
Cash and cash equivalents at end of period	$ (55.9)		$ (34.0)	$ (55.9)		$ (34.0)

[1] (unaudited)