Disclosures About Offsetting Assets And Liabilities (Financial Assets And Derivative Assets That Are Subject To Offset) (Details) - USD ($) $ in Thousands		Sep. 30, 2016	Dec. 31, 2015
Offsetting [Abstract]
Gross amounts of recognized assets, Securities borrowing	[1]	$ 428,274	$ 318,105
Net amounts presented in the Statement of Financial Condition, Securities borrowing	[1]	428,274	318,105
Gross amounts not offset in the Statement of Financial Position, Financial instruments, Securities borrowing	[1]	(263,591)	(182,399)
Gross amounts not offset in the Statement of Financial Position, Collateral received, Securities borrowing	[1]	(153,144)	(123,309)
Securities borrowed, Net amount	[1]	11,539	12,397
Gross amounts of recognized assets, Reverse repurchase agreements	[2]	297,827	160,423
Net amounts presented in the Statement of Financial Condition, Securities purchased under agreements to resell	[2]	297,827	160,423
Gross amounts not offset in the Statement of Financial Position, Financial instruments, Securities purchased under agreements to resell	[2]	(192,385)	(160,423)
Gross amounts not offset in the Statement of Financial Position, Collateral received, Securities purchased under agreements to resell	[2]	(105,442)
Gross amounts of recognized assets		726,101	478,528
Net amounts presented in the Statements of Financial Condition		726,101	478,528
Gross amounts not offset in the Statement of Financial Position		(455,976)	(342,822)
Gross amounts not offset in the Statement of Financial Position, Collateral received		(258,586)	(123,309)
Net amount		$ 11,539	$ 12,397

[1] Securities borrowing transactions are included in receivables from brokers, dealers, and clearing organizations on the consolidated statements of financial condition. See Note 3 in the notes to consolidated financial statements for additional information on receivables from brokers, dealers, and clearing organizations.

[2] Collateral received includes securities received by our company from the counterparty. These securities are not included on the consolidated statements of financial condition unless there is an event of default.