FAIR VALUE MEASUREMENTS (Carrying Value And Fair Value Of Financial Instruments Disclosure) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Fair Value [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	$ 2,352.8	$ 2,346.3
Fair Value [Member] | Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Adjustment to Interest Rate Hedge	1.3	1.4
Carrying Value [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	2,308.2	2,304.2
Carrying Value [Member] | Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Adjustment to Interest Rate Hedge	1.3	1.4
Senior Notes [Member] | Fair Value [Member] | Fair Value, Inputs, Level 1 [Member] | $400 Million 4.875% 2024 Senior Notes [Domain]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	389.0	398.0
Senior Notes [Member] | Fair Value [Member] | Fair Value, Inputs, Level 1 [Member] | $400 Million 5.90% 2020 Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	89.1	88.0
Senior Notes [Member] | Fair Value [Member] | Fair Value, Inputs, Level 1 [Member] | $500 million 4.80% 2020 Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	120.3	118.8
Senior Notes [Member] | Fair Value [Member] | Fair Value, Inputs, Level 1 [Member] | $700 Million 4.875% 2021 Senior Note [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	135.4	130.8
Senior Notes [Member] | Fair Value [Member] | Fair Value, Inputs, Level 1 [Member] | $316 Million 1.5% 2025 Senior Notes [Domain]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	340.0	352.9
Senior Notes [Member] | Fair Value [Member] | Fair Value, Inputs, Level 1 [Member] | $1,075 Million 5.75% 2025 Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	1,026.6	1,029.3
Senior Notes [Member] | Fair Value [Member] | Fair Value, Inputs, Level 1 [Member] | $800 Million 6.25% 2040 Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	251.1	227.1
Senior Notes [Member] | Carrying Value [Member] | Fair Value, Inputs, Level 1 [Member] | $400 Million 4.875% 2024 Senior Notes [Domain]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	390.8	390.3
Senior Notes [Member] | Carrying Value [Member] | Fair Value, Inputs, Level 1 [Member] | $400 Million 5.90% 2020 Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	88.6	88.6
Senior Notes [Member] | Carrying Value [Member] | Fair Value, Inputs, Level 1 [Member] | $500 million 4.80% 2020 Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	122.1	122.0
Senior Notes [Member] | Carrying Value [Member] | Fair Value, Inputs, Level 1 [Member] | $700 Million 4.875% 2021 Senior Note [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	138.0	138.0
Senior Notes [Member] | Carrying Value [Member] | Fair Value, Inputs, Level 1 [Member] | $316 Million 1.5% 2025 Senior Notes [Domain]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	226.8	224.1
Senior Notes [Member] | Carrying Value [Member] | Fair Value, Inputs, Level 1 [Member] | $1,075 Million 5.75% 2025 Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	1,047.9	1,047.2
Senior Notes [Member] | Carrying Value [Member] | Fair Value, Inputs, Level 1 [Member] | $800 Million 6.25% 2040 Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	292.7	292.6
Line of Credit [Member] | Fair Value [Member] | Fair Value, Inputs, Level 2 [Member] | Revolving Credit Facility [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	0.0	0.0
Line of Credit [Member] | Carrying Value [Member] | Fair Value, Inputs, Level 2 [Member] | Revolving Credit Facility [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	$ 0.0	$ 0.0