Available-For-Sale And Held-To-Maturity Securities (Narrative) (Details) (USD $)	3 Months Ended	12 Months Ended
	Jun. 30, 2011	Dec. 31, 2012 security		Dec. 31, 2011		Dec. 31, 2010
Gains or losses recorded in consolidated statement of operations	$ 5,000,000
Carrying value of municipal auction rate securities from held-to-maturity to available-for-sale	27,900,000
Securities available for sale to securities held to maturity	32,900,000
Carrying value of securities pledged as collateral		613,800,000		644,900,000
Available-for-sale securities, Estimated fair value		1,625,168,000		1,214,141,000
Available-for-sale Securities, Amortized cost		1,601,102,000		1,204,205,000
Credit-related other-than-temporary impairment		600,000		1,900,000
Gross unrealized losses related to all other securities		3,394,000	[1]	8,114,000	[1]
Unrealized gains on available-for-sale securities, net of tax		8,684,000		2,103,000		3,132,000
Realized gains resulted from sale of available-for-sale securities		3,800,000		7,900,000
Proceeds from sale of available-for-sale securities		250,200,000		362,100,000
Available-for-sale securities related to individual securities, number of positions		39
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		39
Available-For-Sale Securities [Member]
Available-for-sale securities, Estimated fair value		318,700,000
Available-for-sale securities, percentage of investment portfolio		19.60%
Available-for-sale Securities, Amortized cost		322,100,000
Gross unrealized losses related to all other securities		$ 3,400,000

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