CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interest
Beginning balance (in shares) at Dec. 31, 2016		132,349,534		36,924,102
Balance beginning of period at Dec. 31, 2016	$ 2,976.8	$ 1.3	$ 870.0	$ (839.0)	$ 2,553.3	$ (379.6)	$ 770.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends	(42.2)				(42.2)
Proceeds from treasury stock issued from the exercise of stock options and other benefit plans, net of tax	(2.4)		(7.4)	$ 5.0
Proceeds from treasury stock issued from the exercise of stock options and other benefit plans, net of tax, shares (in shares)				608,920
Stock based compensation	16.7		16.7
Acquisition of Faiveley Transport noncontrolling interest	(742.2)		8.9				(751.1)
Net income (loss)	262.3				262.3
Other comprehensive income, net of tax	334.6					334.6
Acquisition of GE Transportation	25.0		18.4	$ 6.6
Ending balance (in shares) at Dec. 31, 2017		132,349,534		36,315,182
Balance end of period at Dec. 31, 2017	2,828.6	$ 1.3	906.6	$ (827.4)	2,773.4	(45.0)	19.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends	(46.3)				(46.3)
Proceeds from treasury stock issued from the exercise of stock options and other benefit plans, net of tax	(2.2)		(13.5)	$ 11.3
Proceeds from treasury stock issued from the exercise of stock options and other benefit plans, net of tax, shares (in shares)				580,594
Stock based compensation	21.5		21.5
Net income (loss)	291.7				294.9		(3.2)
Other comprehensive income, net of tax	(211.6)					(211.6)
Stock issued for Faiveley Transport Acquisition	(12.6)						(12.6)
Ending balance (in shares) at Dec. 31, 2018		132,349,534		35,734,588
Balance end of period at Dec. 31, 2018	2,869.1	$ 1.3	914.6	$ (816.1)	3,022.0	(256.6)	3.9
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends	(80.3)
Cash dividends	(81.7)				(81.7)
Proceeds from treasury stock issued from the exercise of stock options and other benefit plans, net of tax	(5.6)		(14.6)	$ 9.0
Proceeds from treasury stock issued from the exercise of stock options and other benefit plans, net of tax, shares (in shares)				486,601
Stock based compensation	38.2		38.2
Net income (loss)	326.5				326.7		(0.2)
Other comprehensive income, net of tax	(126.0)					(126.0)
Acquisition of GE Transportation (in shares)		94,597,646
Acquisition of GE Transportation	6,970.3	$ 0.7	6,939.0				30.6
Other owner changes	2.8						2.8
Ending balance (in shares) at Dec. 31, 2019		226,947,180		35,247,987
Balance end of period at Dec. 31, 2019	$ 9,993.6	$ 2.0	$ 7,877.2	$ (807.1)	$ 3,267.0	$ (382.6)	$ 37.1