Quarterly report pursuant to Section 13 or 15(d)

DEBT AND CREDIT FACILITIES (Schedule Of Long-Term Debt) (Details)

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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