Disclosures About Offsetting Assets And Liabilities (Financial Assets And Derivative Assets That Are Subject To Offset) (Details) - USD ($) $ in Thousands		Sep. 30, 2020	Dec. 31, 2019
Offsetting [Abstract]
Gross amounts of recognized assets, Securities borrowing	[1]	$ 178,517	$ 135,373
Net amounts presented in the Statement of Financial Condition, Securities borrowing	[1]	178,517	135,373
Gross amounts not offset in the Statement of Financial Position, Financial instruments, Securities borrowing	[1]	(31,528)	(52,319)
Gross amounts not offset in the Statement of Financial Position, Collateral received, Securities borrowing	[1]	(127,965)	(74,760)
Securities borrowed, Net amount	[1]	19,024	8,294
Gross amounts of recognized assets, Reverse repurchase agreements	[2]	436,860	385,008
Net amounts presented in the Statement of Financial Condition, Securities purchased under agreements to resell	[2]	436,860	385,008
Gross amounts not offset in the Statement of Financial Position, Financial instruments, Securities purchased under agreements to resell	[2]	(48,594)	(59,892)
Gross amounts not offset in the Statement of Financial Position, Collateral received, Securities purchased under agreements to resell	[2]	(384,970)	(325,096)
Securities purchased under agreements to resell, Net amount	[2]	3,296	20
Gross amounts of recognized assets, Cash flow interest rate contracts			1,086
Net amounts presented in the Statement of Financial Condition, Cash flow interest rate contracts			1,086
Cash flow interest rate contracts, Net amount			1,086
Gross amounts of recognized assets		615,377	521,467
Net amounts presented in the Statements of Financial Condition		615,377	521,467
Gross amounts not offset in the Statement of Financial Position		(80,122)	(112,211)
Gross amounts not offset in the Statement of Financial Position, Collateral received		(512,935)	(399,856)
Net amount		$ 22,320	$ 9,400

[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. The fair value of securities pledged as collateral was $433.6 million and $385.3 million at September 30, 2020 and December 31, 2019, respectively.