Debt Security Investments (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Amortized cost, gross unrealized gains, gross unrealized losses and fair values of debt security investments
Amortized Cost	$ 76,009
Total debt security investments, Fair Value	76,030
U.S. Treasury Securities [Member]
Amortized cost, gross unrealized gains, gross unrealized losses and fair values of debt security investments
Amortized Cost	76,009	36,950
Gross Unrealized Gains	29
Gross Unrealized Losses	(8)	(6)
Total debt security investments, Fair Value	$ 76,030	$ 36,944

Amount of debt securities categorized neither as held-to-maturity nor trading.

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+ Details

- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

+ References+ Details