DEBT (Narrative) (Details)		1 Months Ended				3 Months Ended		12 Months Ended
		Oct. 31, 2016	Apr. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Mar. 31, 2014 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Nov. 30, 2015 USD ($)	Jul. 31, 2015 USD ($)	Jun. 30, 2011 USD ($)
Debt Instrument [Line Items]
Transaction fees								$ 7,382,000	$ 0	$ 0
Long term debt	[1]							1,980,464,000	1,984,779,000
Debt issued, amount								2,004,198,000	2,004,459,000				$ 500,000,000
Debt issued, net proceeds				$ 395,207,000
Debt purchased, amount					$ 506,366,000	$ 471,122,000
Total consideration paid for debt			$ 385,024,000		579,659,000			695,060,000	579,829,000	150,602,000
Premium paid for purchase of debt			41,153,000		71,829,000
Transaction cost related to termination of debt			52,000		1,464,000
Other cost (benefit) related to debt purchase			$ 4,136,000		$ (344,000)
Cost of debt purchase						45,341,000		67,075,000	72,949,000	$ 0
10.125% notes due 2015 [Member]
Debt Instrument [Line Items]
Long term debt								$ 0	$ 150,000,000		$ 150,000,000
Interest rate								10.125%	10.125%
Maturity year								2015
4.50% notes due 2025 [Member]
Debt Instrument [Line Items]
Long term debt								$ 400,000,000	$ 0
Debt issued, amount				$ 400,000,000			$ 400,000,000
Interest rate				4.50%			4.50%	4.50%
Maturity year								2025
7.00% notes due 2018 [Member]
Debt Instrument [Line Items]
Long term debt								$ 272,512,000	400,000,000
Interest rate			7.00%	7.00%			7.00%	7.00%
Maturity year								2018
Debt purchased, amount			$ 185,000	$ 127,303,000			$ 127,303,000
Principal amount, percentage			1.00%	32.00%
Total consideration paid for debt				$ 145,899,000
Premium paid for purchase of debt				18,140,000			18,140,000
Transaction cost related to termination of debt				456,000
Other cost (benefit) related to debt purchase				$ 3,138,000
Cost of debt purchase							$ 21,734,000
6.40% notes due 2017 [Member]
Debt Instrument [Line Items]
Long term debt								$ 0	$ 218,633,000
Interest rate			6.40%		6.40%			6.40%	6.40%
Maturity year								2017
Debt purchased, amount			$ 218,633,000		$ 131,367,000
Principal amount, percentage			100.00%
6.50% notes due 2016 [Member]
Debt Instrument [Line Items]
Long term debt								$ 0	$ 125,001,000
Interest rate			6.50%		6.50%			6.50%	6.50%				6.50%
Maturity year								2016
Debt purchased, amount			$ 125,001,000		$ 374,999,000
Principal amount, percentage			100.00%
Bank Line of Credit [Member]
Debt Instrument [Line Items]
Line of credit, maximum borrowing capacity						$ 500,000,000		$ 750,000,000
Transaction fees								$ 2,589,000
Line of credit, expiration date								Jun. 01, 2020
Debt to EBITDA ratio								3.5
EBITDA to net cash interest expense ratio								3.0
Commitment fee								0.25%
Available borrowing capacity								$ 476,136,000
Long term debt								$ 235,000,000
Bank Line of Credit [Member] | Scenario, Forecast [Member]
Debt Instrument [Line Items]
Debt to EBITDA ratio		3.25
Bank Line of Credit [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate								1.75%
Bank Line of Credit [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate								0.75%
Standby Letters of Credit [Member]
Debt Instrument [Line Items]
Other liabilities								$ 38,864,000
Initial term of letters of credit								1 year
Standby Letters of Credit [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate								0.175%
Minimum [Member] | Bank Line of Credit [Member]
Debt Instrument [Line Items]
Commitment fee								0.10%
Minimum [Member] | Bank Line of Credit [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate								1.00%
Minimum [Member] | Bank Line of Credit [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate								0.00%
Maximum [Member] | Bank Line of Credit [Member]
Debt Instrument [Line Items]
Commitment fee								0.35%
Maximum [Member] | Bank Line of Credit [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate								2.00%
Maximum [Member] | Bank Line of Credit [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate								1.00%
Other Notes [Member]
Debt Instrument [Line Items]
Long term debt	[2]							$ 498,000	$ 637,000
Industrial Revenue Bonds [Member]
Debt Instrument [Line Items]
Long term debt								$ 0	$ 14,000,000			$ 14,000,000
Maturity year								2022

[1] The debt balances as of December 31, 2014 have been adjusted to reflect our early adoption of ASU 2015-03 and related election as discussed in Note 1 under the caption New Accounting Standards.

[2] Non-publicly traded debt.