Recovery of Purchase Price from Previous Acquisition - Additional Information (Detail)	1 Months Ended				3 Months Ended
	Feb. 29, 2012 USD ($)	Feb. 29, 2012 GBP (£)	Nov. 30, 2011 USD ($)	Nov. 30, 2011 GBP (£)	Mar. 31, 2012 USD ($)
Business Combination, Separately Recognized Transactions [Line Items]
Proceeds from legal settlement	$ 50,000,000	£ 32,200,000	$ 8,800,000	£ 5,500,000
Pension plan, company contribution	58,000,000	37,700,000
Recovery of purchase price					68,314,000
Expenses incurred in prior periods					5,200,000
Recovery of purchase price, net amount					$ 63,100,000
Settlement agreement date					2012-01-06