Risk Management - Foreign Currency Risk Management (Details) $ in Millions, $ in Millions |
3 Months Ended | |
---|---|---|
Mar. 31, 2019
USD ($)
|
Mar. 31, 2019
CAD ($)
|
|
Cash Flow Hedging [Member] | Foreign currency contracts | ||
Derivative [Line Items] | ||
Derivative, Notional Amount | $ 1,358 | |
Cash Flow Hedging [Member] | 7-yr senior notes | ||
Derivative [Line Items] | ||
Debt Instrument, Term | 7 years | |
Cash Flow Hedging [Member] | 7-yr senior notes | Foreign currency contracts | ||
Derivative [Line Items] | ||
Debt Instrument, Interest Rate, Stated Percentage | 3.79% | 3.79% |
Cash Flow Hedging [Member] | 12-yr senior notes | ||
Derivative [Line Items] | ||
Debt Instrument, Term | 12 years | |
Cash Flow Hedging [Member] | 12-yr senior notes | Foreign currency contracts | ||
Derivative [Line Items] | ||
Debt Instrument, Interest Rate, Stated Percentage | 4.67% | 4.67% |
Net Investment Hedging [Member] | Foreign currency contracts | ||
Derivative [Line Items] | ||
Derivative, Notional Amount | $ 1,888 | $ 2,450 |