SUMMARY OF RESTRICTED STOCK UNITS (Details) (Restricted Stock Units (RSUs) [Member], USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Jun. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Unvested (in shares)	191,026		191,026		203,291
Granted (in shares)	2,400	0	74,724	53,852
Vested (in shares)			(78,305)
Forfeited (in shares)			(8,684)
Unvested, Weighted Average Fair Value (in dollars per share)	$ 52.24		$ 52.24		$ 37.16
Granted, Weighted Average Fair Value (in dollars per share)	$ 62.49		$ 64.27	$ 60.05
Vested in Period, Weighted Average Fair Value (in dollars per share)			$ 25.37
Forfeited in Period, Weighted Average Fair Value (in dollars per share)	$ 45.02		$ 45.02