Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Consolidated Statements of Comprehensive Income
Net margins including noncontrolling interest	$ 52,924	$ 62,853	$ 70,679
Other comprehensive income (loss):
Unrealized loss on securities available for sale	(125)		278
Unrecognized actuarial loss on postretirement benefit obligation	1,528	(4,194)
Reclassification adjustment for actuarial (gain) loss on postretirement benefit obligation included in net income	14	31	(358)
Other comprehensive income (loss)	1,417	(4,163)	(80)
Comprehensive income including noncontrolling interest	54,341	58,690	70,599
Net comprehensive loss attributable to noncontrolling interest	489	1,383	2,233
Comprehensive income attributable to the Association	$ 54,830	$ 60,073	$ 72,832