Pensions and Post-retirement Benefit Plans - Schedule of Pension Plan Assets at Fair Value (Detail) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	$ 212.4	$ 229.5
Quoted prices in active markets for identical assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	66.4	74.4
Significant observable inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	146.0	155.1
Significant unobservable inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
U.S. equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	25.2	28.0
U.S. equity securities [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	15.0	17.5
U.S. equity securities [Member] | Significant observable inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	10.2	10.5
U.S. equity securities [Member] | Significant unobservable inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
International equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	30.7	32.7
International equity securities [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	12.1	12.7
International equity securities [Member] | Significant observable inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	18.6	20.0
International equity securities [Member] | Significant unobservable inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
U.S. debt securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	117.1	128.5
U.S. debt securities [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	32.3	36.4
U.S. debt securities [Member] | Significant observable inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	84.8	92.1
U.S. debt securities [Member] | Significant unobservable inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
International debt securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	32.5	34.6
International debt securities [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	7.0	7.8
International debt securities [Member] | Significant observable inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	25.5	26.8
International debt securities [Member] | Significant unobservable inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
Real estate and other investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	1.4	1.9
Real estate and other investments [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
Real estate and other investments [Member] | Significant observable inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	1.4	1.9
Real estate and other investments [Member] | Significant unobservable inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
Cash & Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	5.5	3.8
Cash & Cash Equivalents [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.0
Cash & Cash Equivalents [Member] | Significant observable inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	5.5	3.8
Cash & Cash Equivalents [Member] | Significant unobservable inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	$ 0.0	$ 0.0