Financial Statements for Guarantors of the Senior Notes - Statement of Cash Flows - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities:
Net income	$ 540.0	$ 67.9	$ 54.0	$ 51.7	$ 74.2	$ 89.6	$ 98.8	$ 102.1	$ 713.6	$ 364.7	$ 826.0
Equity in earnings of subsidiaries, net of taxes									0.0	0.0	0.0
Other									48.0	725.5	113.7
Net cash provided (required) by operating activities									761.6	1,090.2	939.7
Investing activities:
(Increase) decrease in short-term marketable securities									(84.8)	(149.8)	(9.9)
Proceeds from railcar lease fleet sales owned more than one year									360.7	37.7	514.6
Proceeds from disposition of property and other assets									11.3	16.0	8.2
Capital expenditures – leasing									(608.3)	(799.1)	(833.8)
Capital expenditures – manufacturing and other									(104.4)	(134.3)	(196.0)
Acquisitions, net of cash acquired									(47.5)	0.0	(46.2)
(Increase) decrease in investment in partially-owned subsidiaries									0.0	0.0	0.0
Divestitures									0.0	0.0	51.3
Other									0.3	6.8	0.5
Net cash provided (required) by investing activities									(472.7)	(1,022.7)	(511.3)
Financing activities:
Proceeds from issuance of common stock, net									0.0	0.0	0.3
Excess tax benefits from stock-based compensation									0.0	1.0	13.3
Payments to retire debt									(375.4)	(162.5)	(587.2)
Proceeds from issuance of debt									534.1	0.0	242.4
(Increase) decrease in restricted cash									(17.0)	17.6	48.3
Shares repurchased									(79.4)	(34.7)	(115.0)
Dividends paid to common shareholders									(72.6)	(66.7)	(64.9)
Purchase of shares to satisfy employee tax on vested stock									(14.4)	(16.3)	(27.5)
Distributions to noncontrolling interest									(48.7)	(26.4)	(39.2)
Distributions to controlling interest in partially-owned leasing subsidiaries									0.0	0.0	0.0
Change in intercompany financing between entities									0.0	0.0	0.0
Other									(0.3)	(2.1)	(0.8)
Net cash provided (required) by financing activities									(73.7)	(290.1)	(530.3)
Net increase (decrease) in cash and cash equivalents									215.2	(222.6)	(101.9)
Cash and cash equivalents at beginning of period				563.4				786.0	563.4	786.0	887.9
Cash and cash equivalents at end of period	778.6				563.4				778.6	563.4	786.0
Reportable legal entities | Parent
Operating activities:
Net income									702.5	343.6	796.5
Equity in earnings of subsidiaries, net of taxes									(671.4)	(387.5)	(920.0)
Other									137.2	64.5	57.8
Net cash provided (required) by operating activities									168.3	20.6	(65.7)
Investing activities:
(Increase) decrease in short-term marketable securities									(84.8)	(149.8)	(9.9)
Proceeds from railcar lease fleet sales owned more than one year									0.0	0.0	0.0
Proceeds from disposition of property and other assets									0.0	0.0	0.0
Capital expenditures – leasing									0.0	0.0	0.0
Capital expenditures – manufacturing and other									(7.7)	(18.0)	(14.5)
Acquisitions, net of cash acquired									0.0	0.0	0.0
(Increase) decrease in investment in partially-owned subsidiaries									0.0	0.0	0.0
Divestitures									0.0	0.0	0.0
Other									0.0	0.0	0.0
Net cash provided (required) by investing activities									(92.5)	(167.8)	(24.4)
Financing activities:
Proceeds from issuance of common stock, net									0.0	0.0	0.3
Excess tax benefits from stock-based compensation									0.0	1.0	13.3
Payments to retire debt									0.0	0.0	0.0
Proceeds from issuance of debt									0.0	0.0	(1.5)
(Increase) decrease in restricted cash									0.0	0.0	0.0
Shares repurchased									(79.4)	(34.7)	(115.0)
Dividends paid to common shareholders									(72.6)	(66.7)	(64.9)
Purchase of shares to satisfy employee tax on vested stock									(14.4)	(16.3)	(27.5)
Distributions to noncontrolling interest									0.0	0.0	0.0
Distributions to controlling interest in partially-owned leasing subsidiaries									0.0	0.0	0.0
Change in intercompany financing between entities									316.6	33.5	226.0
Other									0.0	0.0	0.0
Net cash provided (required) by financing activities									150.2	(83.2)	30.7
Net increase (decrease) in cash and cash equivalents									226.0	(230.4)	(59.4)
Cash and cash equivalents at beginning of period				537.9				768.3	537.9	768.3	827.7
Cash and cash equivalents at end of period	763.9				537.9				763.9	537.9	768.3
Reportable legal entities | Combined Guarantor Subsidiaries
Operating activities:
Net income									679.4	364.4	844.2
Equity in earnings of subsidiaries, net of taxes									(77.8)	(91.8)	(217.3)
Other									(281.4)	489.2	(36.9)
Net cash provided (required) by operating activities									320.2	761.8	590.0
Investing activities:
(Increase) decrease in short-term marketable securities									0.0	0.0	0.0
Proceeds from railcar lease fleet sales owned more than one year									663.3	27.3	290.6
Proceeds from disposition of property and other assets									1.2	4.1	1.9
Capital expenditures – leasing									(589.8)	(798.7)	(821.6)
Capital expenditures – manufacturing and other									(19.1)	(16.6)	(44.6)
Acquisitions, net of cash acquired									0.0	0.0	0.0
(Increase) decrease in investment in partially-owned subsidiaries									35.0	17.1	24.8
Divestitures									0.0	0.0	0.0
Other									0.0	1.5	0.2
Net cash provided (required) by investing activities									90.6	(765.3)	(548.7)
Financing activities:
Proceeds from issuance of common stock, net									0.0	0.0	0.0
Excess tax benefits from stock-based compensation									0.0	0.0	0.0
Payments to retire debt									(3.8)	(3.6)	(3.2)
Proceeds from issuance of debt									0.0	0.0	0.0
(Increase) decrease in restricted cash									0.0	0.2	(0.2)
Shares repurchased									0.0	0.0	0.0
Dividends paid to common shareholders									0.0	0.0	0.0
Purchase of shares to satisfy employee tax on vested stock									0.0	0.0	0.0
Distributions to noncontrolling interest									0.0	0.0	0.0
Distributions to controlling interest in partially-owned leasing subsidiaries									0.0	0.0	0.0
Change in intercompany financing between entities									(410.6)	10.4	(47.3)
Other									0.0	0.0	0.0
Net cash provided (required) by financing activities									(414.4)	7.0	(50.7)
Net increase (decrease) in cash and cash equivalents									(3.6)	3.5	(9.4)
Cash and cash equivalents at beginning of period				5.2				1.7	5.2	1.7	11.1
Cash and cash equivalents at end of period	1.6				5.2				1.6	5.2	1.7
Reportable legal entities | Combined Non-Guarantor Subsidiaries
Operating activities:
Net income									32.8	50.8	260.3
Equity in earnings of subsidiaries, net of taxes									0.0	0.0	0.0
Other									213.1	205.2	150.2
Net cash provided (required) by operating activities									245.9	256.0	410.5
Investing activities:
(Increase) decrease in short-term marketable securities									0.0	0.0	0.0
Proceeds from railcar lease fleet sales owned more than one year									61.3	10.4	267.2
Proceeds from disposition of property and other assets									10.1	11.9	6.3
Capital expenditures – leasing									(382.4)	(0.4)	(55.4)
Capital expenditures – manufacturing and other									(77.6)	(99.7)	(136.9)
Acquisitions, net of cash acquired									(47.5)	0.0	(46.2)
(Increase) decrease in investment in partially-owned subsidiaries									0.0	0.0	0.0
Divestitures									0.0	0.0	51.3
Other									0.3	5.3	0.3
Net cash provided (required) by investing activities									(435.8)	(72.5)	86.6
Financing activities:
Proceeds from issuance of common stock, net									0.0	0.0	0.0
Excess tax benefits from stock-based compensation									0.0	0.0	0.0
Payments to retire debt									(371.6)	(158.9)	(584.0)
Proceeds from issuance of debt									534.1	0.0	243.9
(Increase) decrease in restricted cash									4.1	13.4	43.3
Shares repurchased									0.0	0.0	0.0
Dividends paid to common shareholders									0.0	0.0	0.0
Purchase of shares to satisfy employee tax on vested stock									0.0	0.0	0.0
Distributions to noncontrolling interest									(48.7)	(26.4)	(39.2)
Distributions to controlling interest in partially-owned leasing subsidiaries									(35.0)	(17.1)	(24.8)
Change in intercompany financing between entities									121.3	7.8	(173.8)
Other									(0.3)	(2.1)	(0.8)
Net cash provided (required) by financing activities									203.9	(183.3)	(535.4)
Net increase (decrease) in cash and cash equivalents									14.0	0.2	(38.3)
Cash and cash equivalents at beginning of period				51.3				51.1	51.3	51.1	89.4
Cash and cash equivalents at end of period	65.3				51.3				65.3	51.3	51.1
Eliminations
Operating activities:
Net income									(701.1)	(394.1)	(1,075.0)
Equity in earnings of subsidiaries, net of taxes									749.2	479.3	1,137.3
Other									(20.9)	(33.4)	(57.4)
Net cash provided (required) by operating activities									27.2	51.8	4.9
Investing activities:
(Increase) decrease in short-term marketable securities									0.0	0.0	0.0
Proceeds from railcar lease fleet sales owned more than one year									(363.9)	0.0	(43.2)
Proceeds from disposition of property and other assets									0.0	0.0	0.0
Capital expenditures – leasing									363.9	0.0	43.2
Capital expenditures – manufacturing and other									0.0	0.0	0.0
Acquisitions, net of cash acquired									0.0	0.0	0.0
(Increase) decrease in investment in partially-owned subsidiaries									(35.0)	(17.1)	(24.8)
Divestitures									0.0	0.0	0.0
Other									0.0	0.0	0.0
Net cash provided (required) by investing activities									(35.0)	(17.1)	(24.8)
Financing activities:
Proceeds from issuance of common stock, net									0.0	0.0	0.0
Excess tax benefits from stock-based compensation									0.0	0.0	0.0
Payments to retire debt									0.0	0.0	0.0
Proceeds from issuance of debt									0.0	0.0	0.0
(Increase) decrease in restricted cash									(21.1)	4.0	5.2
Shares repurchased									0.0	0.0	0.0
Dividends paid to common shareholders									0.0	0.0	0.0
Purchase of shares to satisfy employee tax on vested stock									0.0	0.0	0.0
Distributions to noncontrolling interest									0.0	0.0	0.0
Distributions to controlling interest in partially-owned leasing subsidiaries									35.0	17.1	24.8
Change in intercompany financing between entities									(27.3)	(51.7)	(4.9)
Other									0.0	0.0	0.0
Net cash provided (required) by financing activities									(13.4)	(30.6)	25.1
Net increase (decrease) in cash and cash equivalents									(21.2)	4.1	5.2
Cash and cash equivalents at beginning of period				$ (31.0)				$ (35.1)	(31.0)	(35.1)	(40.3)
Cash and cash equivalents at end of period	$ (52.2)				$ (31.0)				$ (52.2)	$ (31.0)	$ (35.1)