DEBT (Debt) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Debt Instrument [Line Items]
Total short-term debt		$ 0	$ 0	$ 0
Total long-term debt - face value		2,354,064	2,004,065	2,004,194
Unamortized discounts and debt issuance costs		(24,677)	(21,176)	(22,638)
Total long-term debt - book value		2,329,387	1,982,889	1,981,556
Less current maturities		139	138	131
Total long-term debt - reported value		2,329,248	1,982,751	1,981,425
Estimated fair value of long-term debt		2,605,379	2,243,213	2,236,669
Bank Line of Credit [Member]
Debt Instrument [Line Items]
Total short-term debt	[1],[2],[3]	$ 0	0	0
Maturity date		Dec. 31, 2021
Bank Line of Credit [Member]
Debt Instrument [Line Items]
Total long-term debt - face value	[1],[2],[3]	$ 235,000	235,000	235,000
Maturity date		Jun. 01, 2020
Effective interest rate	[1],[2],[3]	1.25%
Notes [Member] | 7.00% notes due 2018 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value		$ 272,512	272,512	272,512
Interest rate		7.00%
Maturity year		2018
Effective interest rate		7.87%
Notes [Member] | 10.375% notes due 2018 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value		$ 250,000	250,000	250,000
Interest rate		10.375%
Maturity year		2018
Effective interest rate		10.63%
Notes [Member] | 7.50% notes due 2021 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value		$ 600,000	600,000	600,000
Interest rate		7.50%
Maturity year		2021
Effective interest rate		7.75%
Notes [Member] | 8.85% notes due 2021 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value		$ 6,000	6,000	6,000
Interest rate		8.85%
Maturity year		2021
Effective interest rate		8.88%
Notes [Member] | Delayed draw term loan [Member]
Debt Instrument [Line Items]
Total long-term debt - face value	[2],[3]	$ 0	0	0
Effective interest rate	[2],[3]	1.25%
Notes [Member] | 4.50% notes due 2025 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value		$ 400,000	400,000	400,000
Interest rate		4.50%
Maturity year		2025
Effective interest rate		4.65%
Notes [Member] | 3.90% notes due 2027 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value		$ 350,000	0	0
Interest rate		3.90%
Maturity year		2027
Effective interest rate		4.06%
Notes [Member] | 7.15% notes due 2037 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value		$ 240,188	240,188	240,188
Interest rate		7.15%
Maturity year		2037
Effective interest rate		8.05%
Other Notes [Member]
Debt Instrument [Line Items]
Total long-term debt - face value	[2]	$ 364	$ 365	$ 494
Effective interest rate	[2]	6.31%

[1] Borrowings on the bank line of credit are classified as short-term debt if we intend to repay within twelve months and as long-term debt if we have the intent and ability to extend payment beyond twelve months.

[2] Non-publicly traded debt.

[3] The effective interest rate is the spread over LIBOR as of the most recent balance sheet date.