Fair Value Measurements (Estimated Fair Values Of Debt Instruments) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Financial Instruments Assets		$ 3,840
Financial Instruments Liabilities		15,735
Carrying Value [Member]
Debt Instrument [Line Items]
Financial Instruments Assets	$ 40,280
Financial Instruments Liabilities	6,177
Level 1
Debt Instrument [Line Items]
Financial Instruments Assets	2,473
Financial Instruments Liabilities	0	3,360
Level 2
Debt Instrument [Line Items]
Financial Instruments Assets	37,807	3,840
Financial Instruments Liabilities	6,177	12,375
NYMEX futures contracts
Debt Instrument [Line Items]
Financial Instruments Liabilities		3,360
NYMEX futures contracts | Carrying Value [Member]
Debt Instrument [Line Items]
Financial Instruments Assets	2,473
NYMEX futures contracts | Level 1
Debt Instrument [Line Items]
Financial Instruments Assets	2,473
Financial Instruments Liabilities		3,360
NYMEX futures contracts | Level 2
Debt Instrument [Line Items]
Financial Instruments Liabilities		0
Foreign currency forward contracts | Carrying Value [Member]
Debt Instrument [Line Items]
Financial Instruments Assets	25,956
Foreign currency forward contracts | Level 2
Debt Instrument [Line Items]
Financial Instruments Assets	25,956
Commodity price swaps
Debt Instrument [Line Items]
Financial Instruments Liabilities		2,424
Commodity price swaps | Carrying Value [Member]
Debt Instrument [Line Items]
Financial Instruments Assets	10,817
Financial Instruments Liabilities	956
Commodity price swaps | Level 2
Debt Instrument [Line Items]
Financial Instruments Assets	10,817
Financial Instruments Liabilities	956	2,424
Commodity forward contracts
Debt Instrument [Line Items]
Financial Instruments Assets		3,840
Financial Instruments Liabilities		1,020
Commodity forward contracts | Carrying Value [Member]
Debt Instrument [Line Items]
Financial Instruments Assets	1,034
Financial Instruments Liabilities	1,137	1,020
Commodity forward contracts | Level 2
Debt Instrument [Line Items]
Financial Instruments Assets	1,034	3,840
Financial Instruments Liabilities	1,137
RINs credit obligations
Debt Instrument [Line Items]
Financial Instruments Liabilities		8,931
RINs credit obligations | Carrying Value [Member]
Debt Instrument [Line Items]
Financial Instruments Liabilities	4,084
RINs credit obligations | Level 2
Debt Instrument [Line Items]
Financial Instruments Liabilities	$ 4,084	$ 8,931