Shareholder's Equity (Schedule of Stock Option Activity (Parenthetical) (Details) (USD $)	3 Months Ended
Mar. 31, 2013
Shareholders' Equity
Total intrinsic value with options exercised	$ 5,691,000
Aggregate intrinsic value of options outstanding	14,059,000
Total intrinsic value of options vested or expected to vest	14,059,000
Total Intrinsic value of options exercisable	$ 14,059,000

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

+ References

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- Definition

The total accumulated difference between fair values of underlying shares on dates of exercise and exercise price on options which were exercised (or share units converted) into shares during the reporting period under the plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of options outstanding.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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- Definition

Amount of difference between fair value of the underlying shares reserved for issuance and exercise prices of fully vested and expected to vest options outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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