Summary of Changes in Accumulated Other Comprehensive Income (Loss) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at Beginning of Period	$ (1,029.2)	$ (863.3)	$ (490.4)
Other comprehensive income (loss) before reclassifications	520.9	(172.8)	(370.5)
Amount reclassified from accumulated other comprehensive loss	20.2	6.9	(2.4)
Net change in accumulated other comprehensive loss	541.1	(165.9)	(372.9)
Balance at End of Period	(488.1)	(1,029.2)	(863.3)
Fair Value Of Derivative Instruments
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at Beginning of Period	(0.6)	(1.1)	(1.8)
Amount reclassified from accumulated other comprehensive loss, change in fair value of derivatives	0.4	0.5	0.7
Net change in accumulated other comprehensive loss	0.4	0.5	0.7
Balance at End of Period	(0.2)	(0.6)	(1.1)
Pension and Other Postretirement Benefit Plan Cost
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at Beginning of Period	(1,085.1)	(907.5)	(604.4)
Other comprehensive income (loss) before reclassifications, Pension and Other Postretirement Benefits Plan Cost	543.9	(184.0)	(300.0)
Amount reclassified from accumulated other comprehensive loss, Pension and Other Postretirement Benefits Plan Cost	19.8	6.4	(3.1)
Net change in accumulated other comprehensive loss	563.7	(177.6)	(303.1)
Balance at End of Period	(521.4)	(1,085.1)	(907.5)
Accumulated Translation Adjustment
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at Beginning of Period	56.5	45.3	115.8
Other comprehensive income (loss) before reclassifications, translation adjustment	(23.0)	11.2	(70.5)
Amount reclassified from accumulated other comprehensive loss, translation adjustment
Net change in accumulated other comprehensive loss	(23.0)	11.2	(70.5)
Balance at End of Period	$ 33.5	$ 56.5	$ 45.3