v3.20.1

Debt (Narrative) (Details) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Feb. 11, 2019 USD ($)
Debt Instrument [Line Items] |  |  |  |
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months | $ 0 |  |  |
Long-term Debt, Maturities, Repayments of Principal in Year Two | 550,000,000 |  |  |
Long-term Debt, Maturities, Repayments of Principal in Year Three | 0 |  |  |
Long-term Debt, Maturities, Repayments of Principal in Year Four | 0 |  |  |
Long-term Debt, Maturities, Repayments of Principal in Year Five | 0 |  |  |
Long-term Debt, Maturities, Repayments of Principal after Year Five | 4,200,000,000 |  |  |
Debt Instrument, Face Amount | 4,750,000,000 | $ 4,300,000,000 |  |
Payment for Debt Extinguishment or Debt Prepayment Cost | 8,270,000 | 0 | $ 0 |
Proceeds from Issuance of Senior Long-term Debt | 996,405,000 | 0 | $ 496,705,000 |
Long-term Debt | $ 4,706,075,000 | $ 4,270,869,000 |  |
Long-term Debt, Weighted Average Interest Rate, over Time | 4.60% | 4.80% | 4.80% |
Cash Payments for Interest | $ 217,100,000 | $ 227,800,000 | $ 206,200,000 |
Revolving Credit Facility [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Line of Credit Facility, Maximum Borrowing Capacity | $ 1,000,000,000.0 |  |  |
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage | 0.125% |  |  |
Letters of Credit Outstanding, Amount | $ 3,500,000 | $ 6,800,000 |  |
Debt Instrument, Consolidated Debt to EBITDA Ratio | 5.0 |  |  |
Revolving Credit Facility [Member] | Minimum [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt Instrument, Basis Spread on Variable Rate | 1.00% |  |  |
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage | 0.10% |  |  |
Revolving Credit Facility [Member] | Maximum [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt Instrument, Basis Spread on Variable Rate | 1.625% |  |  |
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage | 0.275% |  |  |
Commercial Paper [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Line of Credit Facility, Maximum Borrowing Capacity | $ 1,000,000,000.0 |  |  |
Long-term Debt, Weighted Average Interest Rate, over Time | 2.60% | 2.30% |  |
Commercial Paper [Member] | Maximum [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt Instrument, Term | 397 days |  |  |
3.95% Notes due 2050 [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt Instrument, Face Amount | $ 500,000,000.0 | $ 0 |  |
Debt Instrument, Interest Rate, Stated Percentage | 3.95% |  |  |
Debt Instrument, Notes At Price | 99.91% |  |  |
Proceeds from Issuance of Senior Long-term Debt | $ 494,400,000 |  |  |
4.20% Notes Due 2047 [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt Instrument, Face Amount | $ 500,000,000 | 500,000,000 |  |
Debt Instrument, Interest Rate, Stated Percentage | 4.20% |  |  |
4.85% Notes Due 2049 [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt Instrument, Face Amount | $ 500,000,000.0 | 0 |  |
Debt Instrument, Interest Rate, Stated Percentage | 4.85% |  |  |
Payment for Debt Extinguishment or Debt Prepayment Cost | $ 8,300,000 |  |  |
Debt Instrument, Notes At Price | 99.371% |  |  |
Proceeds from Issuance of Senior Long-term Debt | $ 491,500,000 |  |  |
6.55% Notes Due 2019 [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt Instrument, Face Amount | $ 0 | 550,000,000 |  | $ 550,000,000.0
Debt Instrument, Interest Rate, Stated Percentage | 6.55% |  |  | 6.55%
Line of Credit [Member] | Revolving Credit Facility [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Long-term Debt | $ 0 | $ 0 |  |

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