DEBT AND CREDIT FACILITIES (Schedule Of Long-Term Debt) (Details) - USD ($)	Mar. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
LONG-TERM DEBT	$ 2,308,200,000	$ 2,304,200,000	$ 2,304,200,000
$400 Million 4.875% 2024 Senior Notes [Domain]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	5.00%		5.00%
Debt Instrument, Par Value	$ 400,000,000		$ 400,000,000
Unamortized Debt Issuance Expense	(6,700,000)		(7,100,000)
Debt Instrument, Unamortized Discount	(2,500,000)		(2,600,000)
Long-term Debt	$ 390,800,000		$ 390,300,000
$400 Million 5.90% 2020 Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	5.98%		5.98%
Debt Instrument, Par Value	$ 88,900,000		$ 88,900,000
Unamortized Debt Issuance Expense	(200,000)		(200,000)
Debt Instrument, Unamortized Discount	(100,000)		(100,000)
Long-term Debt	$ 88,600,000		$ 88,600,000
$500 million 4.80% 2020 Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	4.83%		4.83%
Debt Instrument, Par Value	$ 122,400,000		$ 122,400,000
Unamortized Debt Issuance Expense	(200,000)		(300,000)
Debt Instrument, Unamortized Discount	(100,000)		(100,000)
Long-term Debt	$ 122,100,000		$ 122,000,000
$700 Million 4.875% 2021 Senior Note [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	4.89%		4.89%
Debt Instrument, Par Value	$ 138,400,000		$ 138,400,000
Unamortized Debt Issuance Expense	(300,000)		(300,000)
Debt Instrument, Unamortized Discount	(100,000)		(100,000)
Long-term Debt	$ 138,000,000		$ 138,000,000
$316 Million 1.5% 2025 Senior Notes [Domain]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	6.26%		6.26%
Debt Instrument, Par Value	$ 316,300,000		$ 316,300,000
Unamortized Debt Issuance Expense	(6,300,000)		(6,600,000)
Debt Instrument, Unamortized Discount	(83,200,000)		(85,600,000)
Long-term Debt	$ 226,800,000		$ 224,100,000
$1,075 Million 5.75% 2025 Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	6.01%		6.01%
Debt Instrument, Par Value	$ 1,075,000,000		$ 1,075,000,000
Unamortized Debt Issuance Expense	(11,100,000)		(11,300,000)
Debt Instrument, Unamortized Discount	(16,000,000)		(16,500,000)
Long-term Debt	$ 1,047,900,000		$ 1,047,200,000
$800 Million 6.25% 2040 Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	6.34%		6.34%
Debt Instrument, Par Value	$ 298,400,000		$ 298,400,000
Unamortized Debt Issuance Expense	(2,300,000)		(2,400,000)
Debt Instrument, Unamortized Discount	(3,400,000)		(3,400,000)
Long-term Debt	292,700,000		292,600,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Par Value	450,000,000		550,000,000
Credit facility, amount outstanding	0		0
Interest Rate Swap [Member]
Debt Instrument [Line Items]
Fair Value Adjustment to Interest Rate Hedge	$ 1,300,000		$ 1,400,000