Stock- Based Compensation (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2012 Y	Mar. 31, 2011 Y
Stock based compensation expense
Stock based compensation	$ 1,391	$ 979
The fair value of options granted
Risk-free interest rate	1.20%	2.70%
Dividend yield	2.70%	1.80%
Expected volatility of the Company's common stock	64.40%	61.50%
Expected life in years	6.0	6.0
Stock Options [Member]
Stock based compensation expense
Stock based compensation	779	493
Restricted Stock Units [Member]
Stock based compensation expense
Stock based compensation	312	282
Performance based units [Member]
Stock based compensation expense
Stock based compensation	$ 300	$ 204

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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