DEBT (Debt) (Details) - USD ($)		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Feb. 28, 2018
Debt Instrument [Line Items]
Total short-term debt		$ 0	$ 133,000,000
Total long-term debt - face value		2,846,373,000	2,846,396,000
Unamortized discounts and debt issuance costs		(62,033,000)	(67,016,000)
Total long-term debt - book value		2,784,340,000	2,779,380,000
Less current maturities		25,000	23,000
Total long-term debt - reported value		2,784,315,000	2,779,357,000
Estimated fair value of long-term debt		3,073,693,000	2,695,802,000
Line of Credit [Member] | Bank Line Of Credit Expires 2021 [Member]
Debt Instrument [Line Items]
Total short-term debt	[1]	$ 0	133,000,000
Maturity year		2021
Line of Credit [Member]
Debt Instrument [Line Items]
Total long-term debt - face value			250,000,000
Line of Credit [Member] | Bank Line Of Credit Expires 2021 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value	[1]	$ 0	0
Notes [Member]
Debt Instrument [Line Items]
Total long-term debt - face value		$ 2,846,373,000
Notes [Member] | Bank Line Of Credit Expires 2021 [Member]
Debt Instrument [Line Items]
Maturity year		2021
Notes [Member] | Floating-Rate Notes Due 2020 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value	[2]	$ 250,000,000	250,000,000
Maturity year		2020
Effective interest rate	[2]	2.89%
Notes [Member] | Floating-Rate Notes Due 2021 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value		$ 500,000,000	500,000,000
Maturity year		2021
Effective interest rate		2.85%
Notes [Member] | 8.85% notes due 2021 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value		$ 6,000,000	6,000,000
Interest rate		8.85%
Maturity year		2021
Effective interest rate		8.88%
Notes [Member] | Term Loan Due 2021 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value			250,000,000
Notes [Member] | 4.50% notes due 2025 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value		$ 400,000,000	400,000,000
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		$ 400,000,000	400,000,000
Interest rate		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		$ 129,239,000	129,239,000	$ 240,188,000
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		$ 700,000,000	700,000,000
Interest rate		4.50%
Maturity year		2047
Effective interest rate		4.59%
Notes [Member] | 4.70% notes due 2048 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value		$ 460,949,000	$ 460,949,000
Interest rate		4.70%	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		$ 185,000	$ 208,000
Effective interest rate		6.46%

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

[2] This debt is classified as long-term since we intend to refinance it, and we have the ability to do so by borrowing on our line of credit.