CONSOLIDATED STATEMENTS OF PATRONAGE CAPITAL AND MEMBERSHIP FEES AND ACCUMULATED OTHER COMPREHENSIVE MARGIN (DEFICIT) (USD $) In Thousands, unless otherwise specified	3 Months Ended				12 Months Ended
	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Increase (Decrease) in Members' Capital
Balance		$ 673,912		$ 634,307	$ 673,912	$ 634,307	$ 595,483
Components of comprehensive margin:
Net margin	(25,150)	22,024	(8,821)	13,520	41,480	39,320	37,737
Unrealized gain (loss) on available-for-sale securities					(1,452)	285	1,087
Total comprehensive margin					40,028	39,605	38,824
Balance	713,940		673,912		713,940	673,912	634,307
Patronage Capital and Membership Fees
Increase (Decrease) in Members' Capital
Balance		673,009		633,689	673,009	633,689	595,952
Components of comprehensive margin:
Net margin					41,480	39,320	37,737
Balance	714,489		673,009		714,489	673,009	633,689
Accumulated Other Comprehensive Margin (Deficit)
Increase (Decrease) in Members' Capital
Balance		903		618	903	618	(469)
Components of comprehensive margin:
Unrealized gain (loss) on available-for-sale securities					(1,452)	285	1,087
Balance	$ (549)		$ 903		$ (549)	$ 903	$ 618