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Debt - Schedule of Commercial Paper (Details) - Commercial Paper - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017
Line of Credit Facility [Line Items] |  |
Commercial paper outstanding | $ 250 | $ 0
Weighted average commercial paper outstanding | $ 580 | $ 170
Weighted average interest rate of commercial paper outstanding | 84.00% | 0.18%

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