Business Acquisitions (Details) shares in Thousands, $ in Thousands, gal in Millions, bu in Millions		12 Months Ended
	Oct. 07, 2014 USD ($) location transaction T shares bu gal	Dec. 31, 2014 USD ($)	May. 18, 2015 USD ($)
Kay Flow Industries, Inc.
Business Acquisition [Line Items]
Percentage of shares outstanding acquired			100.00%
Contingent consideration, minimum			$ 0
Contingent consideration, maximum			24,000
Fair value of consideration for acquisition			125,472
Contingent consideration			400
Working capital adjustment			$ 300
Auburn Bean and Grain
Business Acquisition [Line Items]
Percentage of shares outstanding acquired	100.00%
Number of transactions | transaction	2
Cash payments to acquire businesses	$ 5,000
Shares issued in connection with business acquisition, adjustment to working capital, shares | shares	80
Shares issued in connection with business acquisition, adjustment to working capital, value	$ 4,500
Cash paid to acquire additional facilities	$ 20,400
Additional grain storage capacity acquired (bushels) | bu	18.1
Dry grain storage acquired (tons) | T	16,000
Grain storage acquired, liquid nutrient capacity (gallons) | gal	3.7
Purchase price	$ 60,900
Series of business acquisitions
Business Acquisition [Line Items]
Purchase price		$ 7,200
Grain operations | Auburn Bean and Grain
Business Acquisition [Line Items]
Number of locations acquired | location	6
Agronomy operations | Auburn Bean and Grain
Business Acquisition [Line Items]
Number of locations acquired | location	4
Number of shares issued as part of acquisition | shares	637
Shares issued in connection with business acquisition, value	$ 35,500