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, 2012	Sep. 30, 2012
Beginning Balance	$ 12,000	$ 12,000
Redemptions, Assets	(471)	(471)
Net change, Assets	(471)	(471)
Ending Balance, Assets	11,529	11,529
Corporate Fixed Income Securities [Member]
Beginning Balance	12,808	3,742
Unrealized gains/(losses), Included in changes in net assets		47
Realized gains/(losses), Assets	233	361
Purchases, Assets	2,786	24,694
Sales, Assets	(8,798)	(20,225)
Redemptions, Assets	(434)	(434)
Transfers, Into Level 3, Assets		2,686
Transfers, Out of Level 3, Assets	(3,124)	(7,400)
Net change, Assets	(9,337)	(271)
Ending Balance, Assets	3,471	3,471
State And Municipal Securities [Member]
Beginning Balance	100,730	66,896
Unrealized gains/(losses), Included in OCI, Assets	366	(918)
Realized gains/(losses), Assets		118
Purchases, Assets		37,000
Redemptions, Assets	(17,000)	(19,000)
Net change, Assets	(16,634)	17,200
Ending Balance, Assets	84,096	84,096
Equity Auction Rate Securities [Member]
Beginning Balance	80,037	103,176
Unrealized gains/(losses), Included in changes in net assets	(350)	86
Purchases, Assets	50	2,850
Redemptions, Assets	(11,850)	(38,225)
Net change, Assets	(12,150)	(35,289)
Ending Balance, Assets	67,887	67,887
Municipal Auction Rate Securities [Member]
Beginning Balance	11,503	11,729
Unrealized gains/(losses), Included in changes in net assets	25	94
Purchases, Assets		2,255
Redemptions, Assets	(750)	(3,300)
Net change, Assets	(725)	(951)
Ending Balance, Assets	10,778	10,778
Other [Member]
Beginning Balance	39,091	37,033
Unrealized gains/(losses), Included in changes in net assets	(172)	2,659
Realized gains/(losses), Assets	(132)	521
Purchases, Assets	117	1,361
Sales, Assets	(2,187)	(4,857)
Net change, Assets	(2,374)	(316)
Ending Balance, Assets	$ 36,717	$ 36,717