INCOME TAXES - Summary of reconciliation of statutory federal income tax rate and effective tax rate (Details 4)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax Disclosure [Abstract]
Tax expense at applicable federal rates	34.00%	34.00%	34.00%
State tax, net of federal tax effect	3.60%	2.60%	2.80%
Non-deductible share-based compensation	1.40%	2.20%	3.00%
Non-deductible lobbying expenses	0.70%	0.30%	1.10%
Non-deductible compensation (162m)		2.30%	2.40%
Valuation allowance		3.50%
Domestic production deduction	(5.70%)	(4.20%)	(5.00%)
Federal tax credits		(1.10%)	(2.00%)
State investment tax credit		(2.00%)	(1.40%)
Other	0.70%	0.70%	2.40%
Effective tax expense	34.70%	38.30%	37.30%