Other Comprehensive (Loss) Income - Schedule of Reclassification From Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassification, net of tax	$ (96.9)	$ 63.4	$ (67.6)	$ 61.6
Investment and other (income) expense net	93.1	(0.7)	44.4	(0.6)
Net Actuarial Loss | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Cost of sales; Selling, general and administrative expenses	1.8	7.9	3.5	15.7
Net Prior Service Credit | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Cost of sales; Selling, general and administrative expenses	(0.8)	(4.0)	(1.5)	(8.0)
Settlements | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Cost of sales; Selling, general and administrative expenses		96.9		96.9
Amortization of Pension and Other Postretirement Benefits Plan Cost
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassifications before tax	1.0	100.8	2.0	104.6
Income tax expense (benefit)	0.3	37.4	0.6	43.0
Reclassification, net of tax	0.7	$ 63.4	1.4	$ 61.6
Available-for-Sale Securities, Net Realized Gain on Equity Securities
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassifications before tax	(97.6)		(51.0)
Income tax expense (benefit)			18.0
Reclassification, net of tax	(97.6)		(69.0)
Available-for-Sale Securities, Net Realized Gain on Equity Securities | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Investment and other (income) expense net	$ (97.6)		$ (51.0)