CONSOLIDATED STATEMENTS OF PATRONAGE CAPITAL AND MEMBERSHIP FEES AND ACCUMULATED OTHER COMPREHENSIVE (DEFICIT) MARGIN - USD ($) $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Increase (Decrease) in Members' Capital
Balance		$ 809,523		$ 761,592	$ 809,523	$ 761,592	$ 713,940
Components of comprehensive margin:
Net Margin	$ (12,160)	20,598	$ 6,212	15,369	50,345	48,341	46,635
Unrealized (loss) gain on available-for-sale securities					(428)	(410)	1,017
Total comprehensive margin					49,917	47,931	47,652
Balance	859,440		809,523		859,440	809,523	761,592
Patronage Capital and Membership Fees
Increase (Decrease) in Members' Capital
Balance		809,465		761,124	809,465	761,124	714,489
Components of comprehensive margin:
Net Margin					50,345	48,341	46,635
Balance	859,810		809,465		859,810	809,465	761,124
Accumulated Other Comprehensive (Deficit) Margin
Increase (Decrease) in Members' Capital
Balance		$ 58		$ 468	58	468	(549)
Components of comprehensive margin:
Unrealized (loss) gain on available-for-sale securities					(428)	(410)	1,017
Balance	$ (370)		$ 58		$ (370)	$ 58	$ 468