FAIR VALUE MEASUREMENTS (Carrying Value And Fair Value Of Financial Instruments Disclosure) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Interest Rate Swap [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Adjustment to Interest Rate Hedge		$ 0.2
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	$ 2,187.5	2,039.9
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	0.0	0.2
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	2,109.1	2,092.9
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	0.0	0.2
Senior Notes [Member] | Fair Value [Member] | Fair Value, Inputs, Level 1 [Member] | $400 Million 4.875% 2024 Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	408.9	370.2
Senior Notes [Member] | Fair Value [Member] | Fair Value, Inputs, Level 1 [Member] | $700 Million 4.875% 2021 Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	0.0	122.3
Senior Notes [Member] | Fair Value [Member] | Fair Value, Inputs, Level 1 [Member] | $316.25 Million 1.50% 2025 Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	345.8	352.4
Senior Notes [Member] | Fair Value [Member] | Fair Value, Inputs, Level 1 [Member] | $1.075 Billion 5.75% 2025 Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	466.2	962.0
Senior Notes [Member] | Fair Value [Member] | Fair Value, Inputs, Level 1 [Member] | $750 Million 5.875% 2027 Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	712.2	0.0
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	254.4	232.8
Senior Notes [Member] | Carrying Value [Member] | Fair Value, Inputs, Level 1 [Member] | $400 Million 4.875% 2024 Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	393.2	392.1
Senior Notes [Member] | Carrying Value [Member] | Fair Value, Inputs, Level 1 [Member] | $700 Million 4.875% 2021 Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	0.0	123.8
Senior Notes [Member] | Carrying Value [Member] | Fair Value, Inputs, Level 1 [Member] | $316.25 Million 1.50% 2025 Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	243.8	235.2
Senior Notes [Member] | Carrying Value [Member] | Fair Value, Inputs, Level 1 [Member] | $1.075 Billion 5.75% 2025 Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	463.7	1,048.8
Senior Notes [Member] | Carrying Value [Member] | Fair Value, Inputs, Level 1 [Member] | $750 Million 5.875% 2027 Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt, fair value	715.5	0.0
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	292.9	292.8
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