Goodwill and Other Intangible Assets (Details Textual) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended			12 Months Ended
	Dec. 31, 2016	Jun. 30, 2017	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Goodwill	$ 63,934		$ 63,934		$ 6,024	$ 63,934	$ 63,934	$ 72,365
Goodwill impairment					59,081	0	56,166
Amortization expense for intangible assets					18,100	16,800	14,500
Expected future annual amortization expense of intangibles in 2018					18,900
Expected future annual amortization expense of intangibles in 2019					18,000
Expected future annual amortization expense of intangibles in 2020					16,700
Expected future annual amortization expense of intangibles in 2021					15,700
Expected future annual amortization expense of intangibles in 2022					14,000
Grain
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Goodwill	0		0		1,171	0	0	46,422
Goodwill, accumulated impairment loss					46,400
Goodwill impairment					0		46,422
Retail
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Impairment charges related to software	500
Plant Nutrient
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Goodwill	$ 59,767		59,767		686	$ 59,767	59,767	$ 21,776
Goodwill, accumulated impairment loss					68,900
Goodwill impairment				$ 2,000	59,081		$ 9,744
Plant Nutrient | Wholesale
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Goodwill impairment		$ 42,000			$ 17,100
Long-term earnings growth percentage used to determine impairment or reporting unit					2.00%
Weighted average cost of capital percentage used to determine impairment or reporting unit					10.40%
Plant Nutrient | Grain and Farm Center
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Goodwill impairment			$ 54,200