Securities Available For Sale (Narrative) (Details) (USD $)	12 Months Ended								12 Months Ended		3 Months Ended	12 Months Ended													12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009	Dec. 31, 2011 Auction Rate Securities [Member]	Dec. 31, 2010 Auction Rate Securities [Member]	Jul. 31, 2008 Auction Rate Securities [Member]	Dec. 31, 2011 Auction Rate Securities [Member] Maximum [Member]	Dec. 31, 2011 Auction Rate Securities [Member] Minimum [Member]	Jun. 30, 2011 Auction Rate Securities [Member] Asset Backed Securities Redeemed [Member]	Dec. 31, 2011 Auction Rate Securities [Member] Structured Finance Securities [Member] years		Dec. 31, 2010 Auction Rate Securities [Member] Structured Finance Securities [Member]		Dec. 31, 2009 Auction Rate Securities [Member] Structured Finance Securities [Member]	Dec. 31, 2011 Auction Rate Securities [Member] Structured Finance Securities [Member] Maximum [Member]	Dec. 31, 2011 Auction Rate Securities [Member] Structured Finance Securities [Member] Minimum [Member]	Dec. 31, 2011 Auction Rate Securities [Member] Asset Backed Securities [Member]		Dec. 31, 2010 Auction Rate Securities [Member] Asset Backed Securities [Member]		Dec. 31, 2011 Auction Rate Securities [Member] Asset Backed Securities [Member] Maximum [Member] years	Dec. 31, 2011 Auction Rate Securities [Member] Asset Backed Securities [Member] Minimum [Member] years	Dec. 31, 2010 Auction Rate Securities [Member] Collateralized Debt Obligations Sold [Member]
Investment, debt security, default rate of underlying assets																	9.00%	8.00%
Investment, debt security, default rate of underlying assets												5.56%
Redemption of structured finance auction rate securities											$ 4,600,000
Reversal of unrealized losses on redeemed securities											500,000														900,000
Reversal of unrealized losses on redeemed securities, tax impact											200,000
Proceeds from sale of securities	4,600,000		7,044,000																						7,000,000
Cumulative net realized loss on securities sold																									4,200,000
Auction-rate securities yield rate						1.91%			2.42%	1.60%
Interest earned on auction-rate securities	400,000		700,000		700,000
Impairment of securities available for sale	574,000		1,164,000		6,119,000							600,000		1,200,000		6,100,000
Impairment of securities available for sale														800,000
Cumulative realized losses																									4,200,000
Proceeds from Sale and Maturity of Available-for-sale Securities	4,600,000		7,044,000																						7,000,000
Cumulative credit and other losses recognized in earnings						3,300,000	2,700,000					3,300,000													4,600,000
Gain on sale of securities																									400,000
Par Value of Securities Held						17,900,000	22,500,000	33,700,000				5,000,000													11,200,000
Amortized cost basis	14,600,000	[1]	19,800,000	[1]								1,700,000	[1]	2,300,000	[1]				12,900,000	[1]	17,500,000	[1]			6,600,000
Carrying value of securities	13,565,000		18,997,000											2,600,000
Unrealized gains eliminated from other comprehensive income												300,000
Gross unrealized gains and the corresponding tax impact	(1,000,000)		(800,000)											300,000					(1,000,000)		(1,100,000)
Fair Value	13,600,000		19,000,000									1,700,000		2,600,000					11,900,000		16,400,000				5,700,000
Carrying value	13,600,000		19,000,000									1,700,000		2,600,000					11,900,000		16,400,000				5,700,000
Cumulative unrealized losses included in other comprehensive income																			1,000,000		1,100,000				900,000
Cumulative impact in other comprehensive income, net of tax	7,946,000		6,156,000																600,000		700,000				600,000
Contractual maturities of securities, in years												5											36	16
Gross Cumulative Unrealized (Losses)/Gains	$ (1,000,000)		$ (800,000)											$ 300,000					$ (1,000,000)		$ (1,100,000)

[1] Adjusted cost basis reflects adjustments for credit and other losses recognized in earnings. Cumulative adjustments to the cost basis of securities held as of December 31, 2011 and 2010 totaled $3.3 million and $2.7 million, respectively. Par value of securities held as of December 31, 2011 and 2010 was $17.9 million and $22.5 million, respectively.