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NET INCOME PER SHARE (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Oct. 23, 2013	Dec. 31, 2006
Anti-dilutive Securities Excluded From Computation Of Earnings Per Share
Weighted average number of basic common shares outstanding	52,301,000	50,924,000	49,840,000
Weighted average dilutive stock options, restricted stock units and performance share units	340,000	382,000	501,000
Assumed conversion of Convertible Senior Notes	382,000	1,107,000	985,000
Weighted average number of diluted common and common equivalent shares outstanding	53,023,000	52,413,000	51,326,000
Option indexed to issuer's equity, settlement alternatives, shares, at Fair Value				42,160
Convertible Debt 0.75 Percent Due September 2013
Anti-dilutive Securities Excluded From Computation Of Earnings Per Share
Debt Instrument, Face Amount					$ 172.5
Outstanding Stock Awards
Anti-dilutive Securities Excluded From Computation Of Earnings Per Share
Anti-dilutive potential common shares	2,574,000	2,384,000	2,202,000
Convertible Debt
Anti-dilutive Securities Excluded From Computation Of Earnings Per Share
Anti-dilutive potential common shares	2,100,000	2,000,000	2,000,000