SENIOR NOTES (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Apr. 12, 2011	Apr. 05, 2011	Apr. 02, 2011
Debt Instrument [Line Items]
Long-term debt	$ 856,700,000	$ 686,200,000
Senior Notes [Member]
Debt Instrument [Line Items]
Face Value	405,000,000	405,000,000
Unamortized Net Premium (Discount)	4,000,000	4,600,000
Long-term debt	409,000,000	409,600,000
Senior notes, balance sheet leverage ratio					0.58
Senior Notes [Member] | Maximum [Member]
Debt Instrument [Line Items]
Senior notes, balance sheet leverage ratio					1.50
Senior Notes [Member] | 7.75% Senior Notes Due 2042 [Member]
Debt Instrument [Line Items]
Face Value	55,000,000	55,000,000
Interest Rate	7.75%	7.75%
Public offering price of principal amount		100.00%
Long-term debt	55,000,000	55,000,000
Senior Notes [Member] | 8.75% Senior Notes Due April 1, 2019 [Member]
Debt Instrument [Line Items]
Face Value		100,000,000.0
Interest Rate	8.75%	8.75%
Long-term debt		105,300,000
Senior Notes [Member] | 8.750% Senior Notes Due 2019 [Member]
Debt Instrument [Line Items]
Face Value	350,000,000	350,000,000	50,000,000.0	200,000,000.0
Unamortized Net Premium (Discount)	4,000,000	4,600,000
Interest Rate	8.75%			8.75%	8.75%
Long-term debt	$ 354,000,000	$ 354,600,000	$ 50,800,000	$ 198,600,000