Employee Benefit Plans - Additional Information (Detail) (USD $)	1 Months Ended	12 Months Ended
	Oct. 31, 2010	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Employee Benefit Plan [Line Items]
Defined benefit plan contributions by employer		$ 1,500,000	$ 1,800,000	$ 1,400,000
UNITED KINGDOM
Employee Benefit Plan [Line Items]
Funding valuation period	3 years
Defined benefit plan contributions by employer	800,000	793,000	802,000
Defined benefit plan employers contribution period	10 years 5 months
Defined benefit plan one-time lump-sum payment				1,600,000
Defined benefit plan estimated employer contributions for 2013		800,000
JAPAN
Employee Benefit Plan [Line Items]
Defined benefit plan contributions by employer		324,000	188,000
Defined benefit plan estimated employer contributions for 2013		$ 100,000
Global Equities
Employee Benefit Plan [Line Items]
Defined benefit plan, target plan asset allocations		57.00%
Global Bonds
Employee Benefit Plan [Line Items]
Defined benefit plan, target plan asset allocations		31.00%
Alternative Assets
Employee Benefit Plan [Line Items]
Defined benefit plan, target plan asset allocations		10.00%
Cash
Employee Benefit Plan [Line Items]
Defined benefit plan, target plan asset allocations		2.00%