Employee Benefit Plans - Additional Information (Detail)	12 Months Ended				3 Months Ended	9 Months Ended	12 Months Ended										12 Months Ended										12 Months Ended		12 Months Ended
	Dec. 31, 2013 USD ($)	Dec. 31, 2013 Pension Benefits, U.S. Plans USD ($)	Dec. 31, 2012 Pension Benefits, U.S. Plans USD ($)	Dec. 31, 2011 Pension Benefits, U.S. Plans USD ($)	Dec. 31, 2013 Pension Benefits, Non U.S. Plans USD ($) Rate	Sep. 30, 2013 Pension Benefits, Non U.S. Plans Rate	Dec. 31, 2013 Pension Benefits, Non U.S. Plans USD ($) Rate	Dec. 31, 2013 Pension Benefits, Non U.S. Plans GBP (£)	Dec. 31, 2012 Pension Benefits, Non U.S. Plans USD ($) Rate	Dec. 31, 2012 Pension Benefits, Non U.S. Plans GBP (£)	Dec. 31, 2011 Pension Benefits, Non U.S. Plans USD ($)	Dec. 31, 2011 Pension Benefits, Non U.S. Plans GBP (£)	Dec. 31, 2013 Other Postretirement Benefit Plans USD ($)	Dec. 31, 2012 Other Postretirement Benefit Plans USD ($)	Dec. 31, 2011 Other Postretirement Benefit Plans USD ($)	Dec. 31, 2009 Other Postretirement Benefit Plans USD ($)	Dec. 31, 2013 Equity Securites Pension Benefits, U.S. Plans	Dec. 31, 2013 Equity Securites Pension Benefits, Non U.S. Plans	Dec. 31, 2013 Fixed Maturity Securities Pension Benefits, U.S. Plans	Dec. 31, 2013 Alternative Investments Pension Benefits, U.S. Plans	Dec. 31, 2013 Other Investments Pension Benefits, Non U.S. Plans	Dec. 31, 2013 Minimum Private Equity Funds Pension Benefits, U.S. Plans	Dec. 31, 2013 Maximum Private Equity Funds Pension Benefits, U.S. Plans Integer	Dec. 31, 2013 After Pension Amendment [Member] Pension Benefits, U.S. Plans	Dec. 31, 2013 After Pension Amendment [Member] Pension Benefits, Non U.S. Plans GBP (£) Rate	Dec. 31, 2012 Prior to Pension Amendments [Member] Pension Benefits, U.S. Plans	Dec. 31, 2012 Prior to Pension Amendments [Member] Pension Benefits, Non U.S. Plans	Dec. 31, 2013 After Pension Amendment [Member] Pension Benefits, U.S. Plans	Dec. 31, 2013 After Pension Amendment [Member] Pension Benefits, Non U.S. Plans
Pension and Other Postretirement Benefits Disclosure
Assumptions Used Calculating Benefit Obligation, Discount Rate		5.30%	4.50%		4.40%		4.40%	4.40%	4.50%	4.50%			5.00%	4.20%												4.50%		5.00%	4.60%
Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets		7.50%	7.50%						5.80%	5.80%			5.75%	5.75%													6.20%		6.35%
Incremental Effect on Balance Sheet, Liability or Equity Line Item Change Due to Additional Minimum Pension Liability (AML) Adjustment, Period Increase (Decrease)		$ (327,400,000)					$ (2,300,000)	£ (1,500,000)
Curtailments (Tax Impact)		(114,600,000)
Recognized Net Gain (Loss) Due to Curtailments		(700,000)	0	0			3,700,000	2,300,000	0		0		0	0	0
Maximum Inflation Rate on Pensionable Earnings					2.50%		2.50%	2.50%	5.00%	5.00%
Defined Benefit Plan, Curtailments		126,800,000	0				3,700,000		0				0	4,200,000
Defined Benefit Plan Amendments - Benefit Obligation Impact		0	0				0		0				0	5,000,000
Average Remaining Life Expectancy of Plan Participants							11 years	11 years
Target Plan Asset Allocations																	60.00%	75.00%	30.00%	10.00%	25.00%
Private equity funds, number of years to maturity																						5	8
Level 3 Transfers Into													0	0
Level 3 Transfers Out of													0	0
Interest Rate During Period													5.58%	5.77%
Health Care Cost Trend Rate Assumed for Next Fiscal Year													7.50%	8.00%
Ultimate Health Care Cost Trend Rate													5.00%
Effect of One Percentage Point Increase on Service and Interest Cost Components													200,000
Effect of One Percentage Point Decrease on Service and Interest Cost Components													(100,000)
Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation													2,400,000
Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation													(1,700,000)
Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax		0	600,000		0		0		200,000				(2,400,000)	(7,300,000)		4,400,000
Gross Prescription Drug Subsidy Receipts Received													1,200,000	1,300,000	1,300,000
Amount to be Amortized from Accumulated Other Comprehensive Income (Loss) Next Fiscal Year	(5,600,000)												1,700,000
Amount that will be recognized from AOCI to Income, after tax	(3,700,000)												1,100,000
General Discussion of Pension and Other Postretirement Benefits		We had no regulatory contribution requirements for our U.S. qualified defined benefit plan in 2013
Pension Contributions		50,000,000					4,000,000	2,500,000
Pension Plan Contributions, Percent of Pensionable Earnings					30.00%	24.80%
Estimated Future Employer Contributions in Current Fiscal Year							2,300,000	1,400,000
Employer Matching Contribution, Percent of Employees' Gross Pay		3.00%					5.00%	5.00%																5.00%	5.00%
Employer Matching Contribution on amts over 3%		0.50
Employer Matching Contribution % for $0.50		2.00%
Employer Discretionary Contribution Percentage of earnings							5.00%	5.00%																4.50%	6.00%
Employer Matching Contribution for Every Pound on the First One Percent of Employee Contributions																									2
Employee Contribution Percentage Received 2-for-1 Employer Match																									1.00%
Cost Recognized		$ 18,800,000	$ 18,900,000	$ 18,800,000			$ 2,900,000	£ 1,900,000	$ 2,900,000	£ 1,800,000	$ 2,600,000	£ 1,600,000