Consolidated Statements of Patronage Capital and Membership Fees and Accumulated Other Comprehensive Margin (Deficit) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Increase (Decrease) in Members' Capital
Balance			$ 761,592	$ 713,940
Components of comprehensive margin:
Net margin	$ 10,852	$ 17,196	26,221	36,419
Unrealized (loss) gain on available-for-sale securities	(314)	431	(361)	827
Balance	787,452	751,186	787,452	751,186
Patronage Capital and Membership Fees
Increase (Decrease) in Members' Capital
Balance			761,124	714,489
Components of comprehensive margin:
Net margin			26,221	36,419
Balance	787,345	750,908	787,345	750,908
Accumulated Other Comprehensive Margin (Deficit)
Increase (Decrease) in Members' Capital
Balance			468	(549)
Components of comprehensive margin:
Unrealized (loss) gain on available-for-sale securities			(361)	827
Balance	$ 107	$ 278	$ 107	$ 278