INCOME TAXES (Details) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010	Mar. 31, 2011
INCOME TAXES
Income tax expense	$ 83,089,000	$ 63,254,000	$ 185,820,000	$ 111,565,000
Income before income taxes	198,281,000	155,647,000	512,622,000	304,295,000
Effective tax rate (as a percent)	41.90%	40.60%	36.20%	36.70%
Impact of a pre-tax charge related to change in fair value of a free free-standing derivative instrument	22,100,000
Deferred tax assets related to acquisitions of non-controlling interest	4,100,000		4,100,000			22,100,000
State income tax returns, period subject to examination, low end of range (in years)			3
State income tax returns, period subject to examination, high end of range (in years)			5
Maximum period for which state impact of any federal changes that resulted from the 2006 and 2007 IRS examination remain subject to examination by various states (in years)			1
Federal tax refunds					$ 16,000,000