Balance Sheet Account Detail (Held-to Maturity Marketable Securities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013 securities
Marketable Securities [Abstract]
Gross Unrealized Gain	$ 3
Held to Maturity Securities, Number of Securities Held	7
Fair value of investments, Unrealized Loss Position	15,229
Corporate Debt Securities
Marketable Securities [Abstract]
Amortized Cost	31,313
Gross Unrealized Gain	3
Gross Unrealized Loss	(3)
Fair Value	$ 31,313

This item represents the fair value of securities categorized as held-to-maturity that have been in a continuous unrealized loss position for less than twelve months.

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This item represents the aggregate fair value of investments in debt securities as of the balance sheet date and which are categorized as held-to-maturity.

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- Definition

As of the balance sheet date, the excess of fair value over carrying value (amortized cost) of a debt security categorized as held-to-maturity, exclusive of dividend or interest income recognized but not yet received and exclusive of any write-downs for other-than-temporary impairment. Such item represents the gross unrecognized holding gain.

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- Definition

As of the balance sheet date, the excess of carrying value (amortized cost) over fair value of a debt security categorized as held-to-maturity, exclusive of dividend or interest income recognized but not yet received and exclusive of any write-downs for other-than-temporary impairment. Such item represents the gross unrecognized holding loss.

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