Summary of Significant Accounting Policies (Disaggregation of Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	$ 579,235		$ 903,202
Biomass-based diesel government incentives	915	$ 10,821	366,200	$ 27,762
Total revenues	580,150	$ 535,103	1,269,402	$ 953,996
Biomass-based Diesel
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	540,859		803,967
Biomass-based diesel government incentives	915		366,200
Total revenues	541,774		1,170,167
Services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	17,523		52,738
Biomass-based diesel government incentives	0		0
Total revenues	17,523		52,738
Renewable Chemicals
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	1,063		2,923
Biomass-based diesel government incentives	0		0
Total revenues	1,063		2,923
Corporate and other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	53,173		127,716
Biomass-based diesel government incentives	0		0
Total revenues	53,173		127,716
Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	(33,383)		(84,142)
Biomass-based diesel government incentives	0		0
Total revenues	(33,383)		(84,142)
Biomass-based Diesel
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	473,516		625,603
Biomass-based Diesel | Biomass-based Diesel
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	484,150		648,369
BTC due to customers	0		144,944
Biomass-based Diesel | Services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0		0
Biomass-based Diesel | Renewable Chemicals
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0		0
Biomass-based Diesel | Corporate and other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	6,103		9,682
Biomass-based Diesel | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	(16,737)		(32,448)
Petroleum diesel sales
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	47,070		118,034
Petroleum diesel sales | Biomass-based Diesel
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0		0
Petroleum diesel sales | Services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0		0
Petroleum diesel sales | Renewable Chemicals
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0		0
Petroleum diesel sales | Corporate and other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	47,070		118,034
Petroleum diesel sales | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0		0
Other biomass-based diesel revenue
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	30,523		82,233
Other biomass-based diesel revenue | Biomass-based Diesel
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	30,523		82,233
Other biomass-based diesel revenue | Services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0		0
Other biomass-based diesel revenue | Renewable Chemicals
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0		0
Other biomass-based diesel revenue | Corporate and other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0		0
Other biomass-based diesel revenue | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0		0
Separated RIN sales
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	26,186		73,365
Separated RIN sales | Biomass-based Diesel
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	26,186		73,365
Separated RIN sales | Services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0		0
Separated RIN sales | Renewable Chemicals
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0		0
Separated RIN sales | Corporate and other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0		0
Separated RIN sales | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0		0
Other revenues
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	1,940		3,967
Other revenues | Biomass-based Diesel
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0		0
Other revenues | Services
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	17,523		52,738
Other revenues | Renewable Chemicals
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	1,063		2,923
Other revenues | Corporate and other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0		0
Other revenues | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	$ (16,646)		$ (51,694)