Retirement Benefit Plans - Changes in Plan Assets and Benefit Obligations in AOCL (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Plan, Defined Benefit [Member]
Changes in plan assets and benefit obligations recognized in accumulated other comprehensive loss (AOCL):
AOCL at beginning of year	$ 196.5	$ 578.4
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss), Net Actuarial Gain (Loss), before Tax	41.2	108.4
Recognized net actuarial loss	(14.5)	(31.1)
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements	(15.8)	(456.4)	$ (32.7)
Defined Benefit Plan Accumulated Other Comprehensive Income Foreign Currency Translation Adjustment Before Tax	0.0	0.0
Recognized prior service credit	(1.7)	(2.8)
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments	0.0	0.0	0.0
Total recognized in accumulated other comprehensive loss at December 31	205.7	196.5	578.4
International Plans [Member]
Changes in plan assets and benefit obligations recognized in accumulated other comprehensive loss (AOCL):
AOCL at beginning of year	93.8	133.0
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss), Net Actuarial Gain (Loss), before Tax	20.4	(18.9)
Recognized net actuarial loss	(3.4)	(5.2)
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements	(10.8)	(4.8)	(0.8)
Defined Benefit Plan Accumulated Other Comprehensive Income Foreign Currency Translation Adjustment Before Tax	(11.6)	(9.6)
Recognized prior service credit	(0.1)	(0.1)
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments	0.1	(0.6)	0.0
Total recognized in accumulated other comprehensive loss at December 31	$ 88.4	$ 93.8	$ 133.0
U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.69%