Goodwill and Intangible Assets (Changes in goodwill) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013		Dec. 31, 2012
Goodwill [Roll Forward]
Goodwill at beginning of period	$ 58,554	$ 54,387		$ 12,545
Acquisitions (a)	13,811	4,167		41,842
Goodwill at end of period	72,365	58,554		54,387
Grain
Goodwill [Roll Forward]
Goodwill at beginning of period	38,165	38,165		4,990
Acquisitions (a)	8,257	0	[1]	33,175
Goodwill at end of period	46,422	38,165		38,165
Plant Nutrient
Goodwill [Roll Forward]
Goodwill at beginning of period	13,550	13,550		6,869
Acquisitions (a)	5,554	0		6,681
Goodwill at end of period	19,104	13,550		13,550
Rail
Goodwill [Roll Forward]
Goodwill at beginning of period	4,167	0		0
Acquisitions (a)	0	4,167		0
Goodwill at end of period	4,167	4,167		0
Turf & Specialty
Goodwill [Roll Forward]
Goodwill at beginning of period	2,672	2,672		686
Acquisitions (a)	0	0		1,986
Goodwill at end of period	$ 2,672	$ 2,672		$ 2,672

[1] (a) The Grain acquisition balance has been revised to include the effect of the adjustments to the purchase price allocation in 2013. Discussed in Note 12. Business Acquisitions