DEBT (Debt) (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2019		Dec. 31, 2018		Jun. 30, 2018		Mar. 31, 2018	Feb. 28, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total short-term debt		$ 137,000		$ 133,000		$ 360,000
Total long-term debt - face value		2,846,385		2,846,396		2,846,407
Unamortized discounts and debt issuance costs		(64,535)		(67,016)		(69,478)
Total long-term debt - book value		2,781,850		2,779,380		2,776,929
Less current maturities		24		23		23
Total long-term debt - reported value		2,781,826		2,779,357		2,776,906
Estimated fair value of long-term debt		$ 2,898,283		2,695,802		2,782,543
4.70% notes due 2048 [Member]
Debt Instrument [Line Items]
Maturity year		2048
Bank Line of Credit [Member]
Debt Instrument [Line Items]
Total short-term debt	[1],[2]	$ 137,000		133,000		360,000
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]	0	[1]	0	[1]			$ 250,000
Maturity year		2021
Notes [Member]
Debt Instrument [Line Items]
Total long-term debt - face value		$ 2,846,385
Notes [Member] | Floating-Rate Notes Due 2020 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value	[3]	$ 250,000		250,000		250,000
Maturity year		2020
Effective interest rate	[3]	3.31%
Notes [Member] | Floating-Rate Notes Due 2021 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value		$ 500,000		500,000		500,000
Maturity year		2021
Effective interest rate		3.38%
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] | 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		400,000
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		129,239		129,239				$ 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		700,000
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		$ 460,949		460,949
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		$ 197		$ 208		$ 219
Effective interest rate		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 if we have the intent and ability to extend payment beyond twelve months.

[2] The effective interest rate reflects the margin above LIBOR for LIBOR-based borrowings. We also paid upfront fees that are amortized to interest expense and pay fees for unused borrowing capacity and standby letters of credit.

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