Basis of Presentation - Reclassifications (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2014 USD ($)	Sep. 30, 2015 segment	Sep. 30, 2014 USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Number of reportable segments | segment		4
Hay Sales, Centennial Operations
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Prior year amortization reclassification adjustment	$ 184		$ 588
Hay Sales, Centennial Operations | Cost of Sales
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Prior year amortization reclassification adjustment	$ 374		$ 796