FAIR VALUE OF STOCK UNDER ESPP (Details)	3 Months Ended	6 Months Ended
Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Fair Value Of Stock Under Espp Details
Risk-free interest rate	0.24%	0.23%	0.24%	0.23%
Expected lives, in years	1.2	1.3	1.2	1.3
Expected volatility	36.00%	35.00%	35.00%	34.00%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%

The estimated measure of the maximum 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.

No definition available.

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