Consolidated Statement of Equity - USD ($) $ in Thousands	Patronage capital	Accumulated other comprehensive income (loss)	Noncontrolling interest	Total
Equity at beginning of period at Dec. 31, 2012	$ 802,467	$ 3,415	$ 113,027
Change in Equity
Net margins attributable to the Association	72,912			$ 72,912
Retirement of patronage capital	(10,000)
Unrealized loss on securities available for sale		278
Reclassification adjustment for actuarial (gain)/loss on postretirement benefit obligation included in net income		(358)
Net loss attributable to noncontrolling interest			(2,233)	(2,233)
Equity distribution to noncontrolling interest			(54)
Equity at end of period at Dec. 31, 2013	865,379	3,335	110,740	979,454
Change in Equity
Net margins attributable to the Association	64,236			64,236
Retirement of patronage capital	(20,946)
Unrecognized actuarial loss on postretirement benefit obligation		(4,194)
Reclassification adjustment for actuarial (gain)/loss on postretirement benefit obligation included in net income		31
Net loss attributable to noncontrolling interest			(1,383)	(1,383)
Equity distribution to noncontrolling interest			(55)
Equity at end of period at Dec. 31, 2014	908,669	(828)	109,302	1,017,143
Change in Equity
Net margins attributable to the Association	53,413			53,413
Retirement of patronage capital	(10,000)
Unrealized loss on securities available for sale		(125)
Unrecognized actuarial loss on postretirement benefit obligation		1,528
Reclassification adjustment for actuarial (gain)/loss on postretirement benefit obligation included in net income		14
Net loss attributable to noncontrolling interest			(489)	(489)
Equity distribution to noncontrolling interest			(56)
Equity at end of period at Dec. 31, 2015	$ 952,082	$ 589	$ 108,757	$ 1,061,428