Pensions and Postretirement Benefits Other than Pensions - Weighted Average Assumptions Used to Determine Benefit Obligations (Detail)	Dec. 31, 2012	Dec. 31, 2011
Pension Plans [Member] | United States plan [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	3.92%	4.81%
Rate of compensation increase	0.75%	0.81%
Pension Plans [Member] | Domestic Plans [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	3.75%	4.80%
Pension Plans [Member] | United Kingdom plan [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	4.39%	4.85%
Rate of compensation increase	2.89%	2.99%
Other Postretirement Benefits [Member] | United States plan [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	3.60%	4.15%
Other Postretirement Benefits [Member] | Domestic Plans [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	3.60%	4.15%