Investments (Details 2) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Schedule of unrealized losses and fair values of investments in unrealized loss position aggregated by investment category and length of time that individual securities have been in a continuous loss position
Less than 12 Months, Fair Value		$ 10,568
Less than 12 Months, Unrealized Loss		(5)
Corporate Obligations [Member]
Schedule of unrealized losses and fair values of investments in unrealized loss position aggregated by investment category and length of time that individual securities have been in a continuous loss position
Less than 12 Months, Fair Value		3,810
Less than 12 Months, Unrealized Loss		(1)
U.S. Government notes [Member]
Schedule of unrealized losses and fair values of investments in unrealized loss position aggregated by investment category and length of time that individual securities have been in a continuous loss position
Less than 12 Months, Fair Value		6,758
Less than 12 Months, Unrealized Loss		$ (4)