Available-For-Sale And Held-To-Maturity Securities (Narrative) (Details) (USD $)	3 Months Ended			6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011	Jun. 30, 2012		Jun. 30, 2011	Dec. 31, 2011
Carrying value of securities pledged as collateral	$ 616,000,000			$ 616,000,000			$ 634,800,000
Available-for-sale securities, Estimated fair value	1,329,359,000			1,329,359,000			1,214,141,000
Available-for-sale Securities, Amortized cost	1,312,350,000			1,312,350,000			1,204,205,000
Credit-related other-than-temporary impairment				300,000
Gross unrealized losses related to all other securities	4,812,000	[1]		4,812,000	[1]		8,114,000	[1]
Unrealized gains on available-for-sale securities, net of tax	(492,000)		5,445,000	4,358,000		6,638,000
Realized gains resulted from sale of available-for-sale securities				2,100,000
Proceeds from sale of available-for-sale securities	91,400,000			94,100,000
Available-for-sale securities related to individual securities, number of positions	43			43
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	43			43
Available-For-Sale Securities [Member]
Available-for-sale securities, Estimated fair value	270,400,000			270,400,000
Available-for-sale securities, percentage of investment portfolio	20.30%			20.30%
Available-for-sale Securities, Amortized cost	265,600,000			265,600,000
Gross unrealized losses related to all other securities	$ 4,800,000			$ 4,800,000

[1] Unrealized gains/(losses) related to available-for-sale securities are reported in accumulated other comprehensive loss.