Derivatives (Open Commodity Derivative Contracts) (Details) - Exchange Traded gal in Thousands, bbl in Thousands	12 Months Ended
	Dec. 31, 2019 bbl gal
Crude oil
Derivative [Line Items]
Percentage of derivative contracts expiring next quarter	85.70%
Crude oil | Long
Derivative [Line Items]
Notional contracts (contract volumes)	26,287	[1]
Crude oil | Long | Spread contracts
Derivative [Line Items]
Notional contracts (contract volumes)	5,130
Crude oil | Short
Derivative [Line Items]
Notional contracts (contract volumes) | gal	27,237	[1]
Crude oil | Short | Spread contracts
Derivative [Line Items]
Notional contracts (contract volumes)	330
Refined products
Derivative [Line Items]
Percentage of derivative contracts expiring next quarter	94.70%
Refined products | Long
Derivative [Line Items]
Notional contracts (contract volumes)	15,298	[1]
Refined products | Long | Spread contracts
Derivative [Line Items]
Notional contracts (contract volumes)	950
Refined products | Short
Derivative [Line Items]
Notional contracts (contract volumes) | gal	12,519	[1]
Blending products
Derivative [Line Items]
Percentage of derivative contracts expiring next quarter	99.50%
Blending products | Long
Derivative [Line Items]
Notional contracts (contract volumes)	1,976	[1]
Blending products | Short
Derivative [Line Items]
Notional contracts (contract volumes) | gal	3,770	[1]

[1] Included in exchange-traded are spread contracts in thousands of barrels: Crude oil - 5,130 long and 330 short; Refined products - 950 long and 450 short