Disclosures About Offsetting Assets And Liabilities (Financial Assets And Derivative Assets That Are Subject To Offset) (Details) - USD ($) $ in Thousands		Mar. 31, 2019	Dec. 31, 2018
Offsetting [Abstract]
Gross amounts of recognized assets, Securities borrowing	[1]	$ 115,223	$ 109,795
Net amounts presented in the Statement of Financial Condition, Securities borrowing	[1]	115,223	109,795
Gross amounts not offset in the Statement of Financial Position, Financial instruments, Securities borrowing	[1]	(64,520)	(57,328)
Gross amounts not offset in the Statement of Financial Position, Collateral received, Securities borrowing	[1]	(47,133)	(45,005)
Securities borrowed, Net amount	[1]	3,570	7,462
Gross amounts of recognized assets, Reverse repurchase agreements	[2]	568,034	699,900
Net amounts presented in the Statement of Financial Condition, Securities purchased under agreements to resell	[2]	568,034	699,900
Gross amounts not offset in the Statement of Financial Position, Financial instruments, Securities purchased under agreements to resell	[2]	(28,740)	(365,822)
Gross amounts not offset in the Statement of Financial Position, Collateral received, Securities purchased under agreements to resell	[2]	(539,121)	(329,740)
Securities purchased under agreements to resell, Net amount	[2]	173	4,338
Gross amounts of recognized assets, Cash flow interest rate contracts		4,896	7,683
Net amounts presented in the Statement of Financial Condition, Cash flow interest rate contracts		4,896	7,683
Cash flow interest rate contracts, Net amount		4,896	7,683
Gross amounts of recognized assets		688,153	817,378
Net amounts presented in the Statements of Financial Condition		688,153	817,378
Gross amounts not offset in the Statement of Financial Position		(93,260)	(423,150)
Gross amounts not offset in the Statement of Financial Position, Collateral received		(586,254)	(374,745)
Net amount		$ 8,639	$ 19,483

[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 $568.1 million and $695.6 million at March 31, 2019 and December 31, 2018, respectively.