DEBT (Debt) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018		Feb. 28, 2018	Dec. 31, 2017		Jun. 30, 2017	Mar. 31, 2017
Debt Instrument [Line Items]
Total short-term debt		$ 200,000			$ 0			$ 0
Total long-term debt - face value		2,846,412			2,881,529			2,354,064
Unamortized discounts and debt issuance costs		(70,703)			(26,664)			(24,677)
Total long-term debt - book value		2,775,709			2,854,865			2,329,387
Less current maturities		22			41,383			139
Total long-term debt - reported value		2,775,687			2,813,482			2,329,248
Estimated fair value of long-term debt		2,843,943			2,983,419			2,605,379
Bank Line of Credit [Member]
Debt Instrument [Line Items]
Total short-term debt	[1],[2]	$ 200,000			0			0
Maturity date		Dec. 31, 2021
Effective interest rate	[1],[2]	1.25%
Bank Line of Credit [Member]
Debt Instrument [Line Items]
Total long-term debt - face value		$ 0	[1],[2]		250,000	[1],[2]	$ 235,000	235,000	[1],[2]
Maturity date		Dec. 31, 2021
Term Loan Due 2018 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value	[2],[3]	$ 0			350,000			0
Total long-term debt - book value					350,000
Maturity year		2018
Notes [Member] | 7.00% notes due 2018 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value		$ 0			0			272,512
Interest rate		7.00%
Maturity year		2018
Notes [Member] | 10.375% notes due 2018 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value		$ 0			0			250,000
Interest rate		10.375%
Maturity year		2018
Notes [Member] | Floating-Rate Notes Due 2020 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value		$ 250,000			250,000			0
Maturity year		2020
Effective interest rate		2.50%
Notes [Member] | Floating-Rate Notes Due 2021 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value		$ 500,000			0			0
Maturity year		2021
Effective interest rate		2.69%
Notes [Member] | 7.50% notes due 2021 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value		$ 0			35,111			600,000
Interest rate		7.50%
Maturity year		2021
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		$ 0	[2]		250,000	[2]	$ 250,000	0	[2]
Maturity year		2021
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		$ 400,000			400,000			$ 350,000
Interest rate		3.90%					3.90%	3.90%
Maturity year		2027
Effective interest rate		4.00%
Notes [Member] | 7.15% notes due 2037 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value		$ 129,239			$ 240,188			$ 240,188
Interest rate		7.15%			7.15%
Maturity year		2037
Effective interest rate		8.05%
Notes [Member] | 4.50% notes due 2047 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value		$ 700,000			$ 700,000			0
Interest rate		4.50%					4.50%
Maturity year		2047
Effective interest rate		4.59%
Notes [Member] | 4.70% Percent due 2048 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value		$ 460,949			0			0
Interest rate		4.70%		4.70%
Maturity year		2048
Effective interest rate		5.42%
Other Notes [Member]
Debt Instrument [Line Items]
Total long-term debt - face value	[2]	$ 224			$ 230			$ 364
Effective interest rate	[2]	6.46%

[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 otherwise.

[2] Non-publicly traded debt.

[3] This short-term loan was refinanced on a long-term basis in February 2018 as discussed below. Thus, it was classified as long-term debt as of December 31, 2017