XML 64 R49.htm IDEA: XBRL DOCUMENT v3.8.0.1
Debt - Commercial Paper and Credit Agreement (Details)
3 Months Ended
Mar. 31, 2018
USD ($)
Commercial Paper  
Debt Instrument [Line Items]  
Amount outstanding $ 0
Commercial Paper | Revolving Credit Facility  
Debt Instrument [Line Items]  
Borrowing capacity reserved, commercial paper $ 1,500,000,000
Commercial Paper | Maximum  
Debt Instrument [Line Items]  
Debt term 397 days
Unsecured Debt | Revolving Credit Facility  
Debt Instrument [Line Items]  
Commercial paper program $ 1,500,000,000
Amount outstanding 0
Maximum borrowing capacity 2,000,000,000
Remaining borrowing capacity $ 500,000,000