DEBT (Narrative) (Details) (USD $)	1 Months Ended	3 Months Ended			1 Months Ended																																																		3 Months Ended
	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2013	Jun. 30, 2011	Jun. 30, 2013 Medium-term Notes	Jan. 31, 2013 Medium-term Notes	Mar. 31, 2014 6.50% notes due 2016		Dec. 31, 2013 6.50% notes due 2016		Mar. 31, 2013 6.50% notes due 2016		Mar. 31, 2014 7.50% notes due 2021		Dec. 31, 2013 7.50% notes due 2021		Mar. 31, 2013 7.50% notes due 2021		Mar. 31, 2014 6.30% notes due 2013		Dec. 31, 2013 6.30% notes due 2013		Mar. 31, 2013 6.30% notes due 2013		Mar. 31, 2014 10.125% notes due 2015		Dec. 31, 2013 10.125% notes due 2015		Mar. 31, 2013 10.125% notes due 2015		Mar. 31, 2014 10.375% notes due 2018		Dec. 31, 2013 10.375% notes due 2018		Mar. 31, 2013 10.375% notes due 2018		Mar. 31, 2014 7.00% notes due 2018		Dec. 31, 2013 7.00% notes due 2018		Mar. 31, 2013 7.00% notes due 2018		Mar. 31, 2014 6.40% notes due 2017		Dec. 31, 2013 6.40% notes due 2017		Mar. 31, 2013 6.40% notes due 2017		Mar. 31, 2014 7.15% notes due 2037		Dec. 31, 2013 7.15% notes due 2037		Mar. 31, 2013 7.15% notes due 2037		Mar. 31, 2014 Line of Credit	Mar. 31, 2014 Line of Credit Minimum	Mar. 31, 2014 Line of Credit Maximum
Debt Instrument [Line Items]
Required periodic principal payment		$ 0			$ 140,444,000	$ 10,000,000
Debt instrument face amount				500,000,000
Debt purchased, amount	506,366,000	506,366,000					374,999,000																																				131,367,000
Maturity year							2016	[1]	2016	[1]	2016	[1]	2021	[2]	2021	[2]	2021	[2]	2013	[3]	2013	[3]	2013	[3]	2015	[4]	2015	[4]	2015	[4]	2018	[5]	2018	[5]	2018	[5]	2018	[6]	2018	[6]	2018	[6]	2017	[7]	2017	[7]	2017	[7]	2037	[8]	2037	[8]	2037	[8]
Interest rate				6.50%	6.30%	8.70%	6.50%	[1]	6.50%	[1]	6.50%	[1]	7.50%	[2]	7.50%	[2]	7.50%	[2]	6.30%	[3]	6.30%	[3]	6.30%	[3]	10.125%	[4]	10.125%	[4]	10.125%	[4]	10.375%	[5]	10.375%	[5]	10.375%	[5]	7.00%	[6]	7.00%	[6]	7.00%	[6]	6.40%	[7]	6.40%	[7]	6.40%	[7]	7.15%	[8]	7.15%	[8]	7.15%	[8]
Amount of bank credit facility																																																							500,000,000
Facility expiration date																																																							Mar. 25, 2019
Borrowing capacity	425,750,000	425,750,000
Letter of credit outstanding	53,319,000	53,319,000
Applicable margin for LIBOR based borrowing																																																							2.25%	1.50%	2.25%
Total consideration paid for debt	579,659,000	579,676,000	10,016,000
Premium paid for purchase of debt	71,829,000	71,829,000
Transaction cost related to termination of debt		1,464,000
Other benefit related to debt purchase		344,000
Cost of debt purchase		$ 72,949,000	$ 0

[1] Includes an increase for the unamortized portion of the deferred gain realized upon the August 2011 settlement of interest rate swaps, as follows: March 31, 2014 — $2,677 thousand, December 31, 2013 — $11,627 thousand and March 31, 2013 — $14,221 thousand. The effective interest rate for these notes is 6.00%.

[2] The effective interest rate for these notes is 7.75%.

[3] Includes decreases for unamortized discounts, as follows: March 31, 2013 — $14 thousand.

[4] Includes an increase for the unamortized portion of the deferred gain realized upon the August 2011 settlement of interest rate swaps, as follows: March 31, 2014 — $1,837 thousand, December 31, 2013 — $2,082 thousand and March 31, 2013 — $2,766 thousand. Additionally, includes decreases for unamortized discounts, as follows: March 31, 2014 — $163 thousand, December 31, 2013 — $185 thousand and March 31, 2013 — $246 thousand. The effective interest rate for these notes is 9.58%.

[5] Includes decreases for unamortized discounts, as follows: March 31, 2014 — $1,112 thousand, December 31, 2013 — $1,157 thousand and March 31, 2013 — $1,284 thousand. The effective interest rate for these notes is 10.63%.

[6] Includes decreases for unamortized discounts, as follows: March 31, 2014 — $217 thousand, December 31, 2013 — $228 thousand and March 31, 2013 — $259 thousand. The effective interest rate for these notes is 7.87%.

[7] Includes decreases for unamortized discounts, as follows: March 31, 2014 — $55 thousand, December 31, 2013 — $93 thousand and March 31, 2013 — $108 thousand. The effective interest rate for these notes is 7.41%.

[8] Includes decreases for unamortized discounts, as follows: March 31, 2014 — $624 thousand, December 31, 2013 — $627 thousand and March 31, 2013 — $633 thousand. The effective interest rate for these notes is 8.05%.