Common Stock and Stock Plans, Weighted Average Per Share Fair Value of Options Granted (Details) (USD $)	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Weighted-Average per Share Fair Value of Options Granted and the Assumptions Used [Abstract]
Per share fair value of options granted	$ 3.78	$ 6.11	$ 3.29
Expected Volatility	32.70%	44.30%	53.90%
Expected dividends	$ 0.32	$ 0.20	$ 0.33
Expected term (in years)	1.0	1.3	4.5
Risk-free interest rate	0.20%	0.60%	1.80%

The period of time an equity-based award is expected to be outstanding. An equity-based award's expected term is generally determined based on, among other factors, the instrument's contractual term and the effects of employees' expected exercise and post-vesting employment termination behavior.

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The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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