SHARE-BASED COMPENSATION Stock-Based Compensation - Restricted Liability Units (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock Units Oustanding	165,870	206,120
Restricted Stock Units Outstanding Weighted Average Grant Date Fair Value	$ 20.68	$ 18.53
Restricted Stock Units Granted	51,611	70,110
Restricted Stock Units Granted Weighted Average Grant Date Fair Value	$ 42.08	$ 24.57
Restricted Stock Units Released	(87,509)	(101,420)
Restricted Stock Units Released Weighted Average Grant Date Fair Value	$ 18.47	$ 19.27
Restricted Stock Units Forfeited	(4,918)	(8,940)
Restricted Stock Units Forfeited Weighted Average Grant Date Fair Value	$ 18.97	$ 18.49
Restricted Stock Units Oustanding	125,054	165,870
Restricted Stock Units Outstanding Weighted Average Grant Date Fair Value	$ 31.15	$ 20.68