Retirement Benefit Plans - Benefit Obligation and Plan Assets (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Change in plan assets:
Funded status of plan		$ (186.4)	$ (170.7)
Amounts recognized in Balance Sheet [Abstract]
Non-current liabilities		(301.6)	(294.1)
NSK Warner [Member]
Amounts recognized in accumulated other comprehensive Income Loss) [Abstract]
Net amount	[1]	9.7	10.8
U.S. other postretirement benefit plans [Member]
Change in benefit obligation [Roll Forward]
Projected benefit obligation, January 1		119.9	145.3
Service cost		0.1	0.2	$ 0.2
Interest cost		3.2	4.0	5.7
Plan amendments		(0.7)	0.0
Actuarial loss (gain)		2.2	(14.4)
Acquisition		0.0	0.0
Benefits paid		(17.7)	(15.2)
Projected benefit obligation, December 31		107.0	119.9	145.3
Change in plan assets:
Funded status of plan		(107.0)	(119.9)
Amounts recognized in Balance Sheet [Abstract]
Non-current assets		0.0	0.0
Current liabilities		(13.2)	(14.5)
Non-current liabilities		(93.8)	(105.4)
Net amount		(107.0)	(119.9)
Amounts recognized in accumulated other comprehensive Income Loss) [Abstract]
Net actuarial loss		20.8	19.9
Net prior service (credit) cost		(15.8)	(19.2)
Net amount	[1]	5.0	0.7
United States | Pension Plan [Member]
Change in benefit obligation [Roll Forward]
Projected benefit obligation, January 1		282.5	300.7
Interest cost		8.9	9.6	11.2
Settlement and curtailment				(48.0)
Actuarial loss (gain)		8.7	(5.7)
Acquisition		4.0	0.0
Benefits paid		(20.8)	(22.1)
Projected benefit obligation, December 31		283.3	282.5	300.7
Change in plan assets:
Fair value of plan assets, January 1		229.5	235.8
Actual return on plan assets		23.5	12.7
Employer contribution		4.0	2.7
Settlements				48.0
Acquisition		(3.8)	0.0
Benefits paid		20.7	21.7
Fair value of plan assets, December 31		240.1	229.5	235.8
Funded status of plan		(43.2)	(53.0)
Amounts recognized in Balance Sheet [Abstract]
Non-current assets		0.0	0.0
Current liabilities		(0.1)	(0.1)
Non-current liabilities		(43.1)	(52.9)
Net amount		(43.2)	(53.0)
Amounts recognized in accumulated other comprehensive Income Loss) [Abstract]
Net actuarial loss		111.0	116.9
Net prior service (credit) cost		(6.6)	(7.4)
Net amount	[1]	104.4	109.5
Defined Benefit Plan, Accumulated Benefit Obligation		283.3	282.5
Non-US [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant		0.3	0.4
Change in benefit obligation [Roll Forward]
Projected benefit obligation, January 1		528.2	508.5
Service cost		18.0	16.2	14.9
Interest cost		11.0	12.5	14.1
Plan amendments			0.2
Settlement and curtailment		(3.7)	(1.3)
Actuarial loss (gain)		(7.8)	70.2
Currency translation		63.4	(45.3)
Acquisition		37.0
Divestiture			(12.8)
Benefits paid		(17.6)	(20.4)
Projected benefit obligation, December 31		628.8	528.2	508.5
Change in plan assets:
Fair value of plan assets, January 1		393.8	395.1
Actual return on plan assets		30.7	54.0
Employer contribution		14.3	17.0
Plan participants' contribution		0.3	0.4
Settlements		3.6	1.3
Currency translation		46.8	(40.8)
Divestiture		18.1	10.2
Other		0.6
Benefits paid		17.6	20.4
Fair value of plan assets, December 31		483.4	393.8	$ 395.1
Funded status of plan		(145.4)	(134.4)
Amounts recognized in Balance Sheet [Abstract]
Non-current assets		23.2	4.9
Current liabilities		(3.9)	(3.5)
Non-current liabilities		(164.7)	(135.8)
Net amount		(145.4)	(134.4)
Amounts recognized in accumulated other comprehensive Income Loss) [Abstract]
Net actuarial loss		159.0	163.7
Net prior service (credit) cost		0.8	0.8
Net amount	[1]	159.8	164.5
Defined Benefit Plan, Accumulated Benefit Obligation		$ 602.0	$ 505.5

[1] AOCI shown above does not include our equity investee, NSK-Warner. NSK-Warner had an AOCI loss of $9.7 million and $10.8 million at December 31, 2017 and 2016, respectively.