Goodwill and Other Intangible Assets (Changes in Goodwill) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Goodwill at beginning of period	$ 6,024,000	$ 63,934,000	$ 63,934,000
Acquisitions	0	1,171,000	0
Impairments	0	(59,081,000)	0
Goodwill at end of period	6,024,000	6,024,000	63,934,000
Grain
Goodwill [Roll Forward]
Goodwill at beginning of period		0	0
Acquisitions	0	1,171,000	0
Impairments		0
Goodwill at end of period	1,171,000		0
Plant Nutrient
Goodwill [Roll Forward]
Goodwill at beginning of period	686,000	59,767,000	59,767,000
Acquisitions	0	0	0
Impairments		(59,081,000)
Goodwill at end of period	686,000	686,000	59,767,000
Rail
Goodwill [Roll Forward]
Goodwill at beginning of period	4,167,000	4,167,000	4,167,000
Acquisitions	0	0	0
Impairments		0
Goodwill at end of period	$ 4,167,000	$ 4,167,000	$ 4,167,000