STOCK PLANS (Textual) (Details) (USD $)	12 Months Ended															12 Months Ended				12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Stock options	Dec. 31, 2011 Stock options	Dec. 31, 2010 Stock options	Dec. 31, 2012 Restricted stock awards	Dec. 31, 2011 Restricted stock awards	Dec. 31, 2010 Restricted stock awards	Dec. 31, 2012 Restricted Stock Units	Dec. 31, 2011 Restricted Stock Units	Dec. 31, 2012 1995 Lincoln Stock Purchase Plan	Dec. 31, 2011 1995 Lincoln Stock Purchase Plan	Dec. 31, 2010 1995 Lincoln Stock Purchase Plan	Apr. 28, 2006 EPI Plan	Dec. 31, 2010 EPI Plan Restricted stock awards	Dec. 31, 2012 EPI Plan Restricted Stock Units	Dec. 31, 2011 EPI Plan Restricted Stock Units	Apr. 28, 2006 Director Plan	Dec. 31, 2012 Director Plan Restricted stock awards	Dec. 31, 2011 Director Plan Restricted stock awards	Dec. 31, 2010 Director Plan Restricted stock awards	Dec. 31, 2012 2005 Plan Restricted Stock Units	Dec. 31, 2012 Minimum Restricted stock awards	Dec. 31, 2012 Minimum Restricted Stock Units	Dec. 31, 2012 Maximum Restricted stock awards	Dec. 31, 2012 Maximum Restricted Stock Units	Dec. 31, 2012 Maximum 1995 Lincoln Stock Purchase Plan
Stock Plans
Maximum additional number of the Company's common shares that may be granted (in shares)												800,000			6,000,000				600,000
Common shares available for future grant under all plans (in shares)	2,517,228
Award expiration (in years)				10 years
Award vesting period (in years)				3 years																				3 years	3 years	5 years	5 years
Aggregate intrinsic value of awards outstanding				$ 54,178,000
Aggregate intrinsic value of awards exercisable				47,464,000
Total intrinsic value of awards exercised				18,776,000	10,028,000	4,270,000
Shares converted (in shares)							57,944			10,499	0												10,499
Deferred RSUs (in shares)																							10,713
Shares granted (in shares)							20,099	22,779	112,864	133,944	166,519					82,992	133,944	166,519		20,099	22,779	29,872
Shares granted (in dollars per share)							$ 47.81	$ 35.55	$ 31.05	$ 47.97	$ 34.55					$ 30.97	$ 47.97	$ 34.55		$ 47.81	$ 35.55	$ 31.28
Remaining weighted average life of non-vested restricted awards (in years)							1 year 9 months 18 days			4 years 3 months 18 days
Total stock-based compensation expense	8,961,000	6,610,000	8,213,000
Tax benefit related to stock-based compensation recognized in the period	3,409,000	2,515,000	3,112,000
Total unrecognized stock-based compensation expense related to nonvested stock options, restricted shares and restricted stock units	23,718,000
Weighted average period of recognition of unrecognized stock-based compensation expense (in months)	37 months
Dollar value of shares that each employee has the ability to purchase on the open market, on a commission-free basis annually under the plan																												$ 10,000
Shares purchased (in shares)												4,908	4,466	4,240