Related Party Transactions AgFirst Farm Credit (Details) (USD $)	3 Months Ended							12 Months Ended			15 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Sep. 30, 2012
Related Party Transaction [Line Items]
Common Stock Ownership Percentage by a Related Party	5.00%							5.00%
Guarantee fees	$ 6,568,000	$ 6,401,000	$ 6,064,000	$ 5,930,000	$ 5,966,000	$ 6,320,000	$ 6,387,000	$ 24,963,000	$ 24,821,000	$ 24,091,000	$ 6,148,000
AgFirst Farm Credit Bank [Member]
Related Party Transaction [Line Items]
Guarantee fees								500,000	400,000	400,000
Common stock, Class B Voting | AgFirst Farm Credit Bank [Member]
Related Party Transaction [Line Items]
Common Stock Ownership Percentage by a Related Party	16.80%							16.80%
rural housing [Member] | AgFirst Farm Credit Bank [Member]
Related Party Transaction [Line Items]
Related Party Transactions, Outstanding Balance	168,100,000				231,400,000			168,100,000	231,400,000	299,000,000
Long-Term Standby Purchase Commitments [Member] | AgFirst Farm Credit Bank [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Purchases from Related Party								16,800,000	8,600,000	116,200,000
Related Party Transactions, Outstanding Balance	$ 186,500,000				$ 225,000,000			$ 186,500,000	$ 225,000,000	$ 387,900,000