Goodwill (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Goodwill [Roll Forward]
Balance as of January 1, 2019	$ 6,024
Acquisitions	113,617
Balance as of March 31, 2019	119,641
Trade
Goodwill [Roll Forward]
Balance as of January 1, 2019	1,171
Acquisitions	113,617
Balance as of March 31, 2019	114,788
Plant Nutrient
Goodwill [Roll Forward]
Balance as of January 1, 2019	686
Acquisitions	0
Balance as of March 31, 2019	686
Rail
Goodwill [Roll Forward]
Balance as of January 1, 2019	4,167
Acquisitions	0
Balance as of March 31, 2019	$ 4,167