Hoare Govett Acquisition - Additional Information (Detail)		6 Months Ended
	Feb. 01, 2012 GBP (£)	May 31, 2012 Hoare Govett [Member] USD ($)	Feb. 01, 2012 Hoare Govett [Member] USD ($)	Feb. 01, 2012 Hoare Govett [Member] GBP (£)
Business Acquisition [Line Items]
Business acquisition employee retention payments agreed by acquiree maximum	£ 1,900,000			£ 1,900,000
Cash paid for acquisition				1
Fair values of net assets acquired, including identifiable intangible assets			300,000
Purchase price of net assets acquired			3,100,000
Bargain purchase gain		$ 3,400,000