PROGOLD LIMITED LIABILITY COMPANY (Details) (ProGold Limited Liability Company, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
ProGold Limited Liability Company
ProGold Limited Liability Company
Interest ownership (as a percent)	49.00%
Financial information for ProGold LLC
Current Assets	$ 111	$ 126	$ 132
Long-Term Assets	83,669	92,743	102,815
Total Assets	83,780	92,869	102,947
Current Liabilities	405	406	401
Long-Term Liabilities	1,600	2,000	2,400
Total Liabilities	2,005	2,406	2,801
Members' Equity	81,775	90,463	100,146
Total Liabilities and Members' Equity	83,780	92,869	102,947
Rent Revenue on Operating Lease	25,223	24,063	23,894
Expenses	11,762	11,498	11,445
Net Income	$ 13,461	$ 12,565	$ 12,449