Investments and Fair Value Measurements (Details) (USD $)	3 Months Ended		6 Months Ended		52 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 days	Jun. 30, 2011	Jun. 30, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities
Basis of Tested Impact on Securities	0.50%		0.50%		0.50%
Held-to-maturity Securities	$ 1,300,000		$ 1,300,000		$ 1,300,000	$ 1,300,000
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
Available-for-sale Securities, Debt Maturities, within One Year, Fair Value	0		0		0
Available-for-sale Securities, Debt Maturities, within One Year, Amortized Cost Basis	0		0		0
Available-for-sale Securities, Debt Maturities, after One Through Five Years, Fair Value	0		0		0
Available-for-sale Securities, Debt Maturities, after One Through Five Years, Amortized Cost Basis	0		0		0
Available-for-sale Securities, Debt Maturities, after Five Through Ten Years, Fair Value	0		0		0
Available-for-sale Securities, Debt Maturities, after Five Through Ten Years, Amortized Cost Basis	0		0		0
Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value	21,041,000		21,041,000		21,041,000
Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis	22,325,000		22,325,000		22,325,000
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period			50,569,000	88,694,000
Settlements			(31,325,000)	(21,650,000)
Purchases			0	0
Issuances			0	0
Sales			0	0
Transfers in to (out of) Level 3			0	0
Total gains or losses (realized/unrealized) included in earnings			0	0
Total gains or losses (realized/unrealized) included in other comprehensive loss, net of tax			1,797,000	0
Fair value, end of period	21,041,000	67,044,000	21,041,000	67,044,000	21,041,000
Auction Rate Securities, Debt, Rate Setting Interval (in days)			35
Percent of portfolio with AAA credit rating	100.00%		100.00%		100.00%
Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	(1,300,000)		(1,300,000)		(1,300,000)
Other comprehensive income	1,797,000	0	1,797,000	0
Available-for-sale Securities, Gross Realized Gains (Losses), Sale Proceeds			0	0
Proceeds from Maturities, Prepayments and Calls of Available-for-sale Securities			31,300,000		176,100,000
Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Investment Inputs Average Life of Underlying Loans	2		2		2	2
Investment Inputs Rate of Return	0.53%		0.53%		0.53%	0.68%
Investment Inputs Discount Rate	0.36%		0.36%		0.36%	0.48%
Investment Inputs Liquidity Discount Rate	0.30%		0.30%		0.30%	0.55%
Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Investment Inputs Average Life of Underlying Loans	12		12		12	12
Investment Inputs Rate of Return	3.09%		3.09%		3.09%	2.92%
Investment Inputs Discount Rate	1.15%		1.15%		1.15%	1.14%
Investment Inputs Liquidity Discount Rate	1.05%		1.05%		1.05%	1.16%
Available-for-sale Securities [Member]
Amortized Cost and Fair Value of Investments
Amortized Cost	22,325,000		22,325,000		22,325,000
Fair Value	21,041,000		21,041,000		21,041,000
Auction rate student loan educational bonds long-term
Amortized Cost and Fair Value of Investments
Amortized Cost	22,325,000		22,325,000		22,325,000	53,650,000
Gross Unrealized Gains	0		0		0	0
Gross Unrealized Losses	1,284,000		1,284,000		1,284,000	3,081,000
Fair Value	$ 21,041,000		$ 21,041,000		$ 21,041,000	$ 50,569,000