Pensions and Post Retirement Benefits Other than Pensions - Weighted Average Assumptions Determine Net Periodic Benefit Cost (Detail)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Pension Plans [Member] | United States plan [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	4.83%	5.39%	5.74%
Expected return on plan assets	6.86%	7.58%	8.24%
Rate of compensation increase	0.86%	0.92%	1.03%
Pension Plans [Member] | Domestic Plans [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	4.80%	5.35%	5.75%
Expected return on plan assets	7.00%	7.75%	8.50%
Pension Plans [Member] | United Kingdom plan [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	4.92%	5.50%	5.70%
Expected return on plan assets	6.43%	7.05%	7.44%
Rate of compensation increase	3.17%	3.39%	3.74%
Other Postretirement Benefits [Member] | United States plan [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	4.15%	5.20%	5.75%
Expected return on plan assets
Rate of compensation increase
Other Postretirement Benefits [Member] | Domestic Plans [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	4.15%	5.20%	5.75%
Expected return on plan assets
Other Postretirement Benefits [Member] | United Kingdom plan [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate
Expected return on plan assets
Rate of compensation increase