Accumulated Other Comprehensive Income (Loss) - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Benefit plans expenses reclassified from accumulated OCI to income	$ 11.9	$ 9.7	$ 7.4
Gain/(Loss), Reclassified from AOCI to Income	$ 32.4	$ 6.3	$ 18.2