SHAREHOLDERS' EQUITY (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended		0 Months Ended	1 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	May 05, 2005	May 31, 2004
Shareholders' equity
Options exercised during period (in shares)	1,515,023	621,090
Net proceeds from options exercised during the period	$ 8.4	$ 2.8
Rights Plan
Shareholders' equity
Number of preferred share purchase rights distributed for each share of common stock outstanding (in shares)			1
Specified percentage of market value at which rights become exercisable for the holder, other than the acquirer who acquires 20% or more of the Company's common stock	50.00%
Number of shares that each right entitles the holder to purchase	0.001
Rights Plan | Series RP preferred stock
Shareholders' equity
Period after which an unapproved third party makes, or announces an intention to make, a tender offer or exchange offer for determination of the exercise price	10 days
Rights Plan | Minimum
Shareholders' equity
Percentage of common stock to be acquired for rights to become exercisable for the holder, other than the acquirer at 50% of market value	20.00%
Percentage of common stock to be acquired by the unapproved party for rights to become exercisable for the shareholders with unexercised rights, other than the unapproved party at a value twice the market value	20.00%
ESPP
Shareholders' equity
Number of shares authorized for issuance	2,500,000
Number of shares available for future issuance	536,556
Shares sold	177,036	222,062
Weighted average purchase price of shares sold (in dollars per share)	$ 8.68	$ 4.35
Proceeds from shares sold	$ 1.5	$ 1.0
ESPP | Minimum
Shareholders' equity
Purchase price expressed as percentage of fair market value of common stock				85.00%