Available-For-Sale Securities (Schedule Of Available-For-Sale Securities Portfolio Continuous Unrealized Loss Position) (Details) (USD $) In Thousands	Jun. 30, 2011
Continuous unrealized losses existing for less than 12 months, Fair value	$ 225,963
Continuous unrealized losses existing for less than 12 months, Unrealized losses	(4,711)
Continuous unrealized losses existing for greater than 12 months, Fair value	5,007
Continuous unrealized losses existing for greater than 12 months, Unrealized losses	(936)
Total Fair Value	230,970
Total Unrealized losses	(5,647)
US Treasury [Member]
Continuous unrealized losses existing for less than 12 months, Fair value	98,727
Continuous unrealized losses existing for less than 12 months, Unrealized losses	(3,566)
Total Fair Value	98,727
Total Unrealized losses	(3,566)
US Government Agencies [Member]
Continuous unrealized losses existing for less than 12 months, Fair value	59,539
Continuous unrealized losses existing for less than 12 months, Unrealized losses	(16)
Total Fair Value	59,539
Total Unrealized losses	(16)
Municipal Securities [Member]
Continuous unrealized losses existing for less than 12 months, Fair value	2,463
Continuous unrealized losses existing for less than 12 months, Unrealized losses	(28)
Total Fair Value	2,463
Total Unrealized losses	(28)
Corporate Notes and Other, Financial Issuers [Member]
Continuous unrealized losses existing for less than 12 months, Fair value	61,994
Continuous unrealized losses existing for less than 12 months, Unrealized losses	(1,052)
Continuous unrealized losses existing for greater than 12 months, Fair value	5,007
Continuous unrealized losses existing for greater than 12 months, Unrealized losses	(936)
Total Fair Value	67,001
Total Unrealized losses	(1,988)
Corporate Notes And Other, Other [Member]
Continuous unrealized losses existing for less than 12 months, Fair value	1,012
Continuous unrealized losses existing for less than 12 months, Unrealized losses	(21)
Total Fair Value	1,012
Total Unrealized losses	(21)
Other Equity Securities [Member]
Continuous unrealized losses existing for less than 12 months, Fair value	2,228
Continuous unrealized losses existing for less than 12 months, Unrealized losses	(28)
Total Fair Value	2,228
Total Unrealized losses	$ (28)