Investments and Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	1 Months Ended	3 Months Ended		9 Months Ended		45 Months Ended
	Nov. 04, 2011	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011 days segments divisions locations	Sep. 30, 2010	Nov. 04, 2011	Feb. 14, 2008	Sep. 30, 2011 Auction rate student loan educational bonds current	Dec. 31, 2010 Auction rate student loan educational bonds current	Sep. 30, 2011 Auction rate student loan eductional bonds current total	Dec. 31, 2010 Auction rate student loan eductional bonds current total	Sep. 30, 2011 Auction rate student loan educational bonds long-term	Dec. 31, 2010 Auction rate student loan educational bonds long-term	Sep. 30, 2011 Auction rate student loan eductional bonds long-term total	Dec. 31, 2010 Auction rate student loan eductional bonds long-term total	Sep. 30, 2011 Auction rate student loan educational bonds total	Dec. 31, 2010 Auction rate student loan educational bonds total	Sep. 30, 2011 Minimum [Member] years	Dec. 31, 2010 Minimum [Member] years	Sep. 30, 2011 Maximum [Member] years	Dec. 31, 2010 Maximum [Member] years
Amortized Cost and Fair Value of Investments
Amortized Cost							$ 198,500	$ 11,325	$ 8,300	$ 11,325	$ 8,300	$ 56,225	$ 83,475	$ 56,225	$ 83,475	$ 67,550	$ 91,775
Gross Unrealized Gains								0	0	0	0	0	0	0	0	0	0
Gross Unrealized Losses								0	0	0	0	3,081	3,081	3,081	3,081	3,081	3,081
Fair Value								11,325	8,300	11,325	8,300	53,144	80,394	53,144	80,394	64,469	88,694
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
Available-for-sale Securities, Debt Maturities, within One Year, Fair Value		11,325		11,325
Available-for-sale Securities, Debt Maturities, within One Year, Amortized Cost Basis		11,325		11,325
Available-for-sale Securities, Debt Maturities, after One Through Five Years, Fair Value		0		0
Available-for-sale Securities, Debt Maturities, after One Through Five Years, Amortized Cost Basis		0		0
Available-for-sale Securities, Debt Maturities, after Five Through Ten Years, Fair Value		0		0
Available-for-sale Securities, Debt Maturities, after Five Through Ten Years, Amortized Cost Basis		0		0
Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value		53,144		53,144
Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis		56,225		56,225
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	64,469			88,694	147,419
Settlements				(24,225)	(50,325)
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				0	2,500
Fair value, end of period		64,469	99,594	64,469	99,594
Auction Rate Securities, Debt, Rate Setting Interval (in days)				35
Percent of portfolio with AAA credit rating		100.00%		100.00%
Maturity and calls of investments	11,300	2,600		24,200		142,200
Basis of Tested Impact on Securities		0.50%		0.50%
Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax		(3,081)		(3,081)
Available-for-sale Securities, Gross Realized Gains (Losses), Sale Proceeds		$ 0	$ 0	$ 0	$ 0
Investment Inputs Average Life of Underlying Loans																		2	2	12	12
Investment Inputs Rate of Return																		0.70%	1.28%	2.62%	4.12%
Investment Inputs Discount Rate																		0.28%	0.53%	0.93%	1.85%
Investment Inputs Liquidity Discount Rate																		0.55%	0.40%	0.97%	0.80%