DEBT (Details 1) (USD $)	6 Months Ended				3 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Dec. 31, 2011 Revolving credit facility [Member] Years	Oct. 31, 2011 Revolving credit facility [Member]	Dec. 31, 2011 Revolving credit facility [Member] Minimum [Member]	Dec. 31, 2011 Revolving credit facility [Member] Maximum [Member]	Oct. 31, 2011 Revolving credit facility [Member] Rate 2C [Member] Minimum [Member]	Oct. 31, 2011 Revolving credit facility [Member] Rate 2C [Member] Maximum [Member]	Oct. 31, 2011 LIBOR [Member] Revolving credit facility [Member] Rate 1 [Member] Minimum [Member]	Oct. 31, 2011 LIBOR [Member] Revolving credit facility [Member] Rate 1 [Member] Maximum [Member]	Oct. 31, 2011 LIBOR [Member] Revolving credit facility [Member] Rate 2C [Member]	Oct. 31, 2011 Federal funds rate [Member] Revolving credit facility [Member] Rate 2B [Member]
Debt Instrument
Revolving credit facility				$ 1,000,000,000
Period of revolving credit facility (in years)			5
Applicable margin rate							0.00%	0.50%	1.00%	1.50%
Basis spread on variable rate											1.00%	0.50%
Commitment fee rate					0.10%	0.25%
Letters of credit, maximum amount issuable under credit facility				100,000,000
Line of credit, maximum amount issuable under swingline loans				50,000,000
Letters of credit issued	$ 1,900,000	$ 1,900,000
Line of credit, Interest rate description	Borrowings under the revolving credit facility will bear interest, at the Company's option, at a rate per annum equal to either (i) the adjusted LIBOR for the interest period in effect for such borrowing plus an applicable margin ranging from 1.00% to 1.50%; or (ii) the greatest of (a) JPMorgan Chase Bank, National Association's prime lending rate, (b) the federal funds rate plus 0.50%, and (c) an adjusted LIBOR for an interest period of one month plus 1.00%, plus an applicable margin ranging from 0.00% to 0.50%