Comprehensive Income And Accumulated Other Comprehensive Income - Reclassification out of AOCI (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Gains/(losses) on foreign currency translation adjustments
Liquidation of foreign subsidiary	$ (0.2)		$ 36.6
Cash flow Hedges, net of tax:
Gains (losses) on cash flow hedges - Pre Tax	0.4	$ 11.5	(6.0)
Gains (losses) on cash flow hedges - Tax	(0.2)	(4.8)	2.3
Gains (losses) on cash flow hedges - Net of Tax	0.2	6.7	(3.7)
Gains on available for sale securities:
Gains on available for sale securities - Pre Tax		3.5
Total Gains on available for sale securities		3.5
Pension and other retirement benefits, net of tax:
Amortization of actuarial losses and prior service costs included in net income - Pre Tax	(5.6)	(8.7)	(9.7)
Amortization of actuarial losses and prior service costs included in net income - Tax	1.4	3.3	3.7
Amortization of actuarial losses and prior service costs included in net income - Net of Tax	(4.2)	(5.4)	(6.0)
Income (loss) attributable to reclassification out of AOCI - Net of Tax	(4.2)	3.1	26.9
Other Nonoperating Income (Expense) [Member]
Gains/(losses) on foreign currency translation adjustments
Liquidation of foreign subsidiary	(0.2)		36.6
Operating Expense [Member]
Pension and other retirement benefits, net of tax:
Amortization of actuarial losses and prior service costs included in net income - Pre Tax	(3.7)	(5.5)	(5.8)
SG&A Expenses [Member]
Pension and other retirement benefits, net of tax:
Amortization of actuarial losses and prior service costs included in net income - Pre Tax	(1.9)	(3.2)	(3.9)
Currency Swap [Member] | Other Nonoperating Income (Expense) [Member]
Cash flow Hedges, net of tax:
Gains (losses) on cash flow hedges - Pre Tax	0.5	12.6	(6.0)
Interest Rate Swap [Member] | Interest Income (Expense), Net [Member]
Cash flow Hedges, net of tax:
Gains (losses) on cash flow hedges - Pre Tax	(0.1)	(1.1)
Parent [Member]
Gains on available for sale securities:
Total Gains on available for sale securities		1.8
Pension and other retirement benefits, net of tax:
Income (loss) attributable to reclassification out of AOCI - Net of Tax	$ (4.0)	3.1	$ 26.9
Parent [Member] | Other Nonoperating Income (Expense) [Member]
Gains on available for sale securities:
Gains on available for sale securities - Pre Tax		$ 1.8