Derivatives (Open Commodity Derivative Contracts) (Details) - Exchange Traded gal in Thousands, bbl in Thousands	6 Months Ended
	Jun. 30, 2020 bbl gal
Crude oil
Derivative [Line Items]
Percentage of derivative contracts expiring in the period	94.30%
Crude oil | Long
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels)	46,032	[1]
Crude oil | Long | Spread Contracts
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels)	6,425
Crude oil | Short
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels) | gal	43,019	[1]
Crude oil | Short | Spread Contracts
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels)	2,875
Refined products
Derivative [Line Items]
Percentage of derivative contracts expiring in the period	85.30%
Refined products | Long
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels)	24,489	[1]
Refined products | Long | Spread Contracts
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels)	1,525
Refined products | Short
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels) | gal	18,100	[1]
Refined products | Short | Spread Contracts
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels)	225
Blending products
Derivative [Line Items]
Percentage of derivative contracts expiring in the period	86.00%
Blending products | Long
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels)	1,067	[1]
Blending products | Short
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels) | gal	2,842	[1]

[1] Included in exchange-traded are spread contracts in thousands of barrels: Crude oil - 6,425 long and 2,875 short; Refined products - 1,525 long and 225 short