Accumulated Other Comprehensive Income (Schedule Of Accumulated Other Comprehensive Income) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended		12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011	Dec. 31, 2010
Accumulated Other Comprehensive Income [Abstract]
AOCI, Unrealized gains on available-for-sale securities, beginning balance	$ 53,911	$ 31,962	$ 31,962
Other Comprehensive Income, Unrealized gains on available-for-sale securities	6,551	18,093
AOCI, Unrealized gains on available-for-sale securities, ending balance	60,462	50,055	53,911	31,962
AOCI, Unrealized losses on securities for which other-than-temporary-impairment has been recognized, beginning balance	(29,299)	(28,926)	(29,299)	(28,173)
Other Comprehensive Income, Unrealized losses on securities for which other-than-temporary-impairment has been recognized	0	(753)
AOCI, Unrealized losses on securities for which other-than-temporary-impairment has been recognized, ending balance	(29,299)	(28,926)	(29,299)	(28,173)
AOCI, Unrealized gains (losses) on held-to-maturity securities, beginning balance	4,468	5,087	4,745	5,667
Other Comprehensive Income, Unrealized gains (losses) on held-to-maturity securities	(277)	(580)
AOCI, Unrealized gains (losses) on held-to-maturity securities, ending balance	4,468	5,087	4,745	5,667
AOCI, Unrecognized gain (loss) on cash flow hedges, beginning balance	1	568	145	846
Other Comprehensive Income, Unrecognized gain (loss) on cash flow hedges	(144)	(278)
AOCI, Unrecognized gain (loss) on cash flow hedges, ending balance	1	568	145	846
AOCI, Defined benefit pension plans, beginning balance	(13,290)	(10,382)	(14,498)	(11,571)
Other Comprehensive Income, Defined benefit pension plans	1,208	1,189
AOCI, Defined benefit pension plans, ending balance	(13,290)	(10,382)	(14,498)	(11,571)
Accumulated other comprehensive income (loss), beginning balance	15,004	(1,269)	(1,269)
Other Comprehensive Income, Accumulated other comprehensive income (loss)	7,338	17,671
Accumulated other comprehensive income (loss), ending balance	$ 22,342	$ 16,402	$ 15,004	$ (1,269)