Collateralized Transactions - Contractual Maturity (Details) $ in Thousands	Aug. 31, 2015 USD ($)
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities Lending Arrangements	$ 3,645,195
Repurchase Agreements	19,478,562
Total	23,123,757
Overnight and Continuous [Member]
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities Lending Arrangements	1,954,916
Repurchase Agreements	9,827,633
Total	11,782,549
Up to 30 Days [Member]
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities Lending Arrangements	336,335
Repurchase Agreements	4,539,795
Total	4,876,130
30-90 Days [Member]
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities Lending Arrangements	1,353,944
Repurchase Agreements	2,869,691
Total	4,223,635
Greater than 90 Days [Member]
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities Lending Arrangements	0
Repurchase Agreements	2,241,443
Total	$ 2,241,443