Postretirement Benefit Plans - Other Changes in Plan Assets and Net Periodic Postretirement Cost Recognized in Other Comprehensive Income (Loss) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net periodic postretirement cost
Service cost	$ 6.3	$ 9.5
Interest cost	22.9	22.9
Amortization of prior service cost	0	0	0
Effect of curtailment / Special termination benefit		1.2
Other changes in plan assets and benefit obligations recognized in other comprehensive loss
Prior service cost		0	0
U.S. Pension Plans [Member]
Net periodic postretirement cost
Service cost	3.2	4.9	4.8
Interest cost	13.1	12.1	12.9
Expected return on plan assets	(20.0)	(19.5)	(18.2)
Amortization of net actuarial loss (gain)	5.8	8.3	6.5
Amortization of prior service cost	0.6	0.8	0.9
Net periodic postretirement cost	2.7	6.6	6.9
Effect of curtailment / Special termination benefit	0	1.2	0
Total net periodic postretirement cost	2.7	7.8	6.9
Other changes in plan assets and benefit obligations recognized in other comprehensive loss
Net actuarial (gain) loss	37.0	(40.0)	19.8
Prior service cost	4.5	0	0
Amortization of net actuarial (loss) gain	(5.8)	(8.3)	(6.5)
Amortization of prior service cost	(0.6)	(0.8)	(0.9)
Foreign currency translation	0	0	0
Total change recognized in other comprehensive loss	35.1	(49.1)	12.4
Total impact from net periodic postretirement cost and changes in other comprehensive loss	37.8	(41.3)	19.3
International Pension Plan [Member]
Net periodic postretirement cost
Service cost	1.6	1.7	1.0
Interest cost	2.4	2.5	2.5
Expected return on plan assets	(0.1)	(0.1)	(0.1)
Amortization of net actuarial loss (gain)	0.4	0.6	(0.2)
Net periodic postretirement cost	4.3	4.7	3.2
Effect of curtailment / Special termination benefit	0.4	0	0
Total net periodic postretirement cost	4.7	4.7	3.2
Other changes in plan assets and benefit obligations recognized in other comprehensive loss
Net actuarial (gain) loss	13.7	(1.8)	14.8
Prior service cost	0	0	0
Amortization of net actuarial (loss) gain	(0.9)	(0.6)	0.2
Amortization of prior service cost	0	0	0
Foreign currency translation	(1.8)	0.5	0.4
Total change recognized in other comprehensive loss	11.0	(1.9)	15.4
Total impact from net periodic postretirement cost and changes in other comprehensive loss	15.7	2.8	18.6
Pension [Member]
Net periodic postretirement cost
Service cost	4.8	6.6	5.8
Interest cost	15.5	14.6	15.4
Expected return on plan assets	(20.1)	(19.6)	(18.3)
Amortization of net actuarial loss (gain)	6.2	8.9	6.3
Amortization of prior service cost	0.6	0.8	0.9
Net periodic postretirement cost	7.0	11.3	10.1
Effect of curtailment / Special termination benefit	0.4	1.2	0
Total net periodic postretirement cost	7.4	12.5	10.1
Other changes in plan assets and benefit obligations recognized in other comprehensive loss
Net actuarial (gain) loss	50.7	(41.8)	34.6
Prior service cost	4.5
Amortization of net actuarial (loss) gain	(6.7)	(8.9)	(6.3)
Amortization of prior service cost	(0.6)	(0.8)	(0.9)
Foreign currency translation	(1.8)	0.5	0.4
Total change recognized in other comprehensive loss	46.1	(51.0)	27.8
Total impact from net periodic postretirement cost and changes in other comprehensive loss	53.5	(38.5)	37.9
Other Postretirement Benefit Plan [Member]
Net periodic postretirement cost
Service cost	1.5	2.9	2.5
Interest cost	7.4	8.3	9.5
Expected return on plan assets	(0.7)	(0.6)	(0.5)
Amortization of net actuarial loss (gain)	2.7	4.3	4.6
Amortization of prior service cost	(6.6)	(0.4)	(0.1)
Total net periodic postretirement cost	4.3	14.5	16.0
Other changes in plan assets and benefit obligations recognized in other comprehensive loss
Net actuarial (gain) loss	26.3	(31.1)	22.1
Prior service cost	(58.7)	(19.0)	(3.1)
Amortization of net actuarial (loss) gain	(2.7)	(4.3)	(4.6)
Amortization of prior service cost	6.6	0.4	0.1
Total change recognized in other comprehensive loss	(28.5)	(54.0)	14.5
Total impact from net periodic postretirement cost and changes in other comprehensive loss	$ (24.2)	$ (39.5)	$ 30.5