Retirement Plans and Other Post-Retirement Benefits - Schedule of Change in Benefit Obligation and Plan Assets (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Change in Plan Assets
Fair value of plan assets at beginning of year	$ 594.9
Fair value of plan assets at end of year	610.7	$ 594.9
Pension Benefits [Member]
Change in Benefit Obligation
Balance at beginning of year	541.9	577.6
Service cost	10.5	11.6	$ 10.4
Interest cost	24.5	23.3	24.8
Plan amendments	5.5
Actuarial (gain)/loss	17.0	(34.8)
Benefits paid	(22.9)	(34.8)
One-time settlement	(24.2)
Effect of currency rate changes	(0.3)	(1.0)
Balance at end of year	552.0	541.9	577.6
Change in Plan Assets
Fair value of plan assets at beginning of year	594.9	638.0
Actual return on plan assets	60.8	(10.3)
Total contributions	2.1	2.0
Benefits paid	(22.9)	(34.8)
One-time settlement	(24.2)
Fair value of plan assets at end of year	610.7	594.9	638.0
Funded status at end of year	58.7	53.0
Other Benefits [Member]
Change in Benefit Obligation
Balance at beginning of year	51.0	59.8
Service cost	1.1	1.4	1.5
Interest cost	2.0	2.0	2.5
Participant contributions	1.0	1.2
Actuarial (gain)/loss	(3.4)	(10.1)
Benefits paid	(3.8)	(3.3)
Balance at end of year	47.9	51.0	$ 59.8
Change in Plan Assets
Total contributions	3.8	3.3
Benefits paid	(3.8)	(3.3)
Funded status at end of year	$ (47.9)	$ (51.0)