Balance Sheet Accounts (Schedule of Available-for-sale Investments by Contractual Maturity) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012
Amortized Cost
Due in 1 year or less	$ 35,125
Due in 1-2 years	31,367
Due in 2-5 years	39,722
Total investments in available for sale debt securities	106,214
Fair Value
Due in 1 year or less	35,204
Due in 1-2 years	31,447
Due in 2-5 years	39,761
Total investments in available for sale debt securities	$ 106,412

Available-for-sale Securities, Debt Maturities, After Year One and Before Two, Amortized Cost Basis

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Available-for-sale Securities, Debt Maturities, After Year Two Through Five, Amortized Cost Basis

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Amount of available-for-sale debt securities at cost, net of adjustments, which include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

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Amount of available-for-sale debt securities at cost, net of adjustments, maturing in the next fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

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