Debt - Narrative (Details) |
3 Months Ended | ||
---|---|---|---|
Jun. 30, 2017
USD ($)
|
Mar. 31, 2019
USD ($)
|
Dec. 31, 2018
USD ($)
|
|
Debt Instrument [Line Items] | |||
Long-term debt, fair value | $ 4,000,000,000 | $ 3,800,000,000 | |
Five-Year Credit Agreement | Maximum | |||
Debt Instrument [Line Items] | |||
Indebtedness to cash flow (not greater than) | 4 | ||
Five-Year Credit Agreement | Revolving Credit Facility | |||
Debt Instrument [Line Items] | |||
Maximum borrowing capacity | $ 1,200,000,000.0 | ||
Credit facility, term (in years) | 5 years | ||
Commitment fee | 0.10% | ||
Five-Year Credit Agreement | Revolving Credit Facility | Minimum | |||
Debt Instrument [Line Items] | |||
Commitment fee | 0.08% | ||
Five-Year Credit Agreement | Revolving Credit Facility | Maximum | |||
Debt Instrument [Line Items] | |||
Commitment fee | 0.175% | ||
Five-Year Credit Agreement | Commercial paper | |||
Debt Instrument [Line Items] | |||
Maximum borrowing capacity | $ 1,200,000,000.0 | ||
Short-term debt | $ 0 | $ 0 |