Securities Available For Sale (Schedule of Auction Rate Securities Redeemed and Sold) (Details) (USD $)	3 Months Ended		6 Months Ended			39 Months Ended											3 Months Ended	42 Months Ended		3 Months Ended	42 Months Ended		3 Months Ended	42 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Auction Rate Securities [Member]	Dec. 31, 2012 Auction Rate Securities [Member]		Jun. 30, 2013 Auction Rate Securities [Member] Fair Value [Member]	Dec. 31, 2012 Auction Rate Securities [Member] Fair Value [Member]	Jun. 30, 2013 Auction Rate Securities [Member] Asset-backed Securities [Member]		Dec. 31, 2012 Auction Rate Securities [Member] Asset-backed Securities [Member]		Dec. 31, 2012 Auction Rate Securities [Member] Collateralized Debt Obligations [Member]		Dec. 31, 2012 Auction Rate Securities [Member] Collateralized Debt Obligations [Member] Fair Value [Member]	Jun. 30, 2013 Auction Rate Securities [Member] Securities Redeemed or Sold [Member]	Mar. 31, 2013 Auction Rate Securities [Member] Securities Redeemed or Sold [Member]	Mar. 31, 2013 Auction Rate Securities [Member] Securities Redeemed or Sold [Member] Fair Value [Member]	Jun. 30, 2013 Auction Rate Securities [Member] Securities Redeemed or Sold [Member] Asset-backed Securities [Member]	Mar. 31, 2013 Auction Rate Securities [Member] Securities Redeemed or Sold [Member] Asset-backed Securities [Member]	Mar. 31, 2013 Auction Rate Securities [Member] Securities Redeemed or Sold [Member] Asset-backed Securities [Member] Fair Value [Member]	Jun. 30, 2013 Auction Rate Securities [Member] Securities Redeemed or Sold [Member] Collateralized Debt Obligations [Member]	Mar. 31, 2013 Auction Rate Securities [Member] Securities Redeemed or Sold [Member] Collateralized Debt Obligations [Member]	Mar. 31, 2013 Auction Rate Securities [Member] Securities Redeemed or Sold [Member] Collateralized Debt Obligations [Member] Fair Value [Member]
Schedule of Available-for-sale Securities [Line Items]
Auction rate securities, par value					$ 10,300,000	$ 17,900,000												$ 7,600,000			$ 2,600,000			$ 5,000,000
Cumulative credit and other losses recognized in earnings, auction rate securities sold					0	(3,300,000)												(3,300,000)			0			(3,300,000)
Adjusted cost basis						14,600,000	[1]			10,300,000	[1]	12,900,000	[1]	1,700,000	[1]			4,300,000			2,600,000			1,700,000
Available-for-sale securities, gross unrealized gain (loss)						(200,000)												1,100,000			(200,000)			1,300,000
Auction rate securities, fair value								9,300,000	14,400,000							2,700,000			5,400,000			2,400,000			3,000,000
Proceeds from sale or redemption of investments			5,025,000	0													5,000,000			2,600,000			2,400,000
Reversal of unrealized (gains) losses	(388,000)	0	(388,000)	0													(400,000)			200,000			(600,000)
Available-for-sale securities, gross realized gains			$ (717,000)	$ 0													$ (700,000)			$ 0			$ (700,000)

[1] Adjusted cost basis reflects adjustments for credit and other losses recognized in earnings on our structured finance security. There were no adjustments to the cost basis of securities held as of June 30, 2013. Cumulative adjustments to the cost basis of securities held as of December 31, 2012 totaled $3.3 million. Par value of securities held as of June 30, 2013 and December 31, 2012 totaled $10.3 million and $17.9 million, respectively.