Fair Value Of Financial Instruments (Schedule Of Changes In Fair Value Carrying Values Associated With Level 3 Financial Instruments) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013		Sep. 30, 2013
Corporate Fixed Income Securities [Member]
Beginning Balance	$ 5,057		$ 583
Unrealized gains/(losses), Included in changes in net assets	(29)	[1]	434	[1]
Realized gains/(losses), Assets	101	[1]	281	[1]
Purchases, Assets	398		9,362
Sales, Assets	(2,707)		(6,888)
Redemptions, Assets	(259)		(1,347)
Transfers, Into Level 3, Assets	2		139
Transfers, Out of Level 3, Assets	(1,766)		(1,767)
Net change, Assets	(4,260)		214
Ending Balance, Assets	797		797
Equity Securities [Member]
Beginning Balance	12,601
Unrealized gains/(losses), Included in changes in net assets			1,333	[1]
Purchases, Assets			11,476
Sales, Assets			(208)
Transfers, Out of Level 3, Assets	(12,601)		(12,601)
Net change, Assets	(12,601)
State And Municipal Securities [Member]
Beginning Balance	81,930	[2]	90,487	[3]
Unrealized gains/(losses), Included in OCI, Assets	329	[2],[4]	(1,840)	[3],[4]
Realized gains/(losses), Assets	383	[1],[2]	895	[1],[3]
Purchases, Assets			5,000	[3]
Redemptions, Assets	(5,000)	[2]	(16,900)	[3]
Transfers, Into Level 3, Assets	6,201	[2]	6,201	[3]
Transfers, Out of Level 3, Assets	(5,408)	[2]	(5,408)	[3]
Net change, Assets	(3,495)	[2]	(12,052)	[3]
Ending Balance, Assets	78,435	[2],[3]	78,435	[2],[3]
Equity Auction Rate Securities [Member]
Beginning Balance	62,109		64,397
Unrealized gains/(losses), Included in changes in net assets	519	[1]	206	[1]
Purchases, Assets			75
Redemptions, Assets	(2,900)		(4,950)
Net change, Assets	(2,381)		(4,669)
Ending Balance, Assets	59,728		59,728
Municipal Auction Rate Securities [Member]
Beginning Balance	13,330		14,067
Unrealized gains/(losses), Included in changes in net assets	31	[1]	(6)	[1]
Redemptions, Assets	(952)		(1,652)
Net change, Assets	(921)		(1,658)
Ending Balance, Assets	12,409		12,409
Other Investment [Member]
Beginning Balance	86,994		37,297
Unrealized gains/(losses), Included in changes in net assets	3,514	[1]	9,245	[1]
Realized gains/(losses), Assets	(632)	[1]	(129)	[1]
Purchases, Assets	2,127		50,804
Sales, Assets	(2,602)		(6,801)
Redemptions, Assets	(1,096)		(2,111)
Transfers, Into Level 3, Assets	12,601		12,601
Net change, Assets	13,912		63,609
Ending Balance, Assets	$ 100,906		$ 100,906

[1] Realized and unrealized gains/(losses) related to trading securities and investments are reported in other income in the consolidated statements of operations.

[2] Included in available-for-sale securities owned in the consolidated statements of financial condition

[3] Included in available-for-sale securities owned in the consolidated statements of financial condition.

[4] Unrealized gains/(losses) related to available-for-sale securities are reported in accumulated other comprehensive loss in the consolidated statements of financial condition.