Fair Value (Details 2) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Summary of available-for-sale securities
Amortized Cost	$ 65,638	$ 23,809
Gross Unrealized Gains	40	40
Gross Unrealized Losses	(30)	(11)
Total	65,648	23,838
State, municipal and local government agencies bonds [Member]
Summary of available-for-sale securities
Amortized Cost	34,135	11,915
Gross Unrealized Gains	37	20
Gross Unrealized Losses	(5)	(4)
Total	34,167	11,931
U.S. federal, state, municipal and local government agencies bonds [Member]
Summary of available-for-sale securities
Amortized Cost	8,584
Gross Unrealized Gains	3
Gross Unrealized Losses	(1)
Total	8,586
Corporate bonds [Member]
Summary of available-for-sale securities
Amortized Cost	18,321	11,894
Gross Unrealized Gains		20
Gross Unrealized Losses	(24)	(7)
Total	18,297	11,907
Commercial Paper [Member]
Summary of available-for-sale securities
Amortized Cost	4,598
Total	$ 4,598

For an unclassified balance sheet, total of debt securities categorized neither as held-to-maturity nor trading.

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+ Details