Derivative Instruments and Hedging Activities - Amounts Included in OCI, Income and AOCI (Details) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | ||
---|---|---|---|---|
Sep. 30, 2018 |
Sep. 30, 2017 |
Sep. 30, 2018 |
Sep. 30, 2017 |
|
Revenues [Member] | ||||
Derivative Instruments, Gain (Loss) [Line Items] | ||||
Gain (loss) reclassified from OCI into income (effective portion) | $ (23.9) | $ (2.1) | $ (58.3) | $ (2.2) |
Commodity Contracts [Member] | Revenues [Member] | Not Designated as Hedging Instrument [Member] | ||||
Derivative Instruments, Gain (Loss) [Line Items] | ||||
Gain (loss) recognized in income on derivatives | (1.1) | (1.5) | (14.1) | (2.9) |
Cash Flow Hedging [Member] | Commodity Contracts [Member] | ||||
Derivative Instruments, Gain (Loss) [Line Items] | ||||
Gain (loss) recognized in OCI on derivatives (effective portion) | $ (139.6) | $ (106.8) | $ (178.0) | $ (10.5) |