Reclassification out of AOCI (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Cash Flow Hedges, net of tax:
Gains on cash flow hedges - Pre Tax	$ 4.2	$ 1.3	$ 11.7	$ 0.9
Gains (losses) on cash flow hedges - Tax	(1.6)	(0.4)	(4.9)	(0.3)
Gains on cash flow hedges - Net of Tax	2.6	0.9	6.8	0.6
Available for sale securities:
Gains on available for sale securities - Pre Tax	2.2		2.2
Gains on available for sale securities	2.2		2.2
Pension and Other Post-Retirement Benefits, net of tax:
Amortization of actuarial losses and prior service costs included in net income - Pre Tax	(2.1)	(2.4)	(6.4)	(7.3)
Amortization of actuarial losses and prior service costs included in net income - Tax	0.8	0.9	2.5	2.8
Amortization of actuarial losses and prior service costs included in net income - Net of Tax	(1.3)	(1.5)	(3.9)	(4.5)
Income Loss Attributable to Reclassification Out Of AOCI Net Of Tax	2.4	(0.6)	4.0	(3.9)
Parent [Member]
Available for sale securities:
Gains on available for sale securities - Pre Tax	1.1		1.1
Gains on available for sale securities	1.1		1.1
Operating Expense [Member]
Pension and Other Post-Retirement Benefits, net of tax:
Amortization of actuarial losses and prior service costs included in net income - Pre Tax	(1.3)	(1.5)	(4.0)	(4.6)
Other Nonoperating Income (Expense) [Member] | Parent [Member]
Available for sale securities:
Gains on available for sale securities - Pre Tax	1.1		1.1
SG&A Expense [Member]
Pension and Other Post-Retirement Benefits, net of tax:
Amortization of actuarial losses and prior service costs included in net income - Pre Tax	(0.8)	(0.9)	(2.4)	(2.7)
Cross-Currency Swap [Member] | Other Nonoperating Income (Expense) [Member]
Cash Flow Hedges, net of tax:
Gains on cash flow hedges - Pre Tax	3.5	$ 1.3	12.1	$ 0.9
Interest Rate Contract [Member] | Interest Expense [Member]
Cash Flow Hedges, net of tax:
Gains on cash flow hedges - Pre Tax	$ 0.7		$ (0.4)