Statements Of Changes In Equities And Margins (USD $)	3 Months Ended				12 Months Ended
	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Balance		$ 161,231,426		$ 161,842,284	$ 161,231,426	$ 161,842,284	$ 156,320,597
Assignable margins	3,373,971	3,423,068	3,211,146	3,640,027	5,525,507	5,573,262	5,410,009
Retirement of capital credits					(48,079)	(6,761,968)	(94,278)
Unclaimed capital credit retirements					(12,949)	367,277	90,320
Memberships and donations received					68,468	210,571	115,636
Balance	166,764,373		161,231,426		166,764,373	161,231,426	161,842,284
Memberships [Member]
Balance		1,517,488		1,474,869	1,517,488	1,474,869	1,432,054
Assignable margins					0	0	0
Retirement of capital credits					0	0	0
Unclaimed capital credit retirements					0	0	0
Memberships and donations received					41,856	42,619	42,815
Balance	1,559,344		1,517,488		1,559,344	1,517,488	1,474,869
Other Equities And Margins [Member]
Balance		11,358,692		10,823,463	11,358,692	10,823,463	10,660,322
Assignable margins					0	0	0
Retirement of capital credits					0	0	0
Unclaimed capital credit retirements					(12,949)	367,277	90,320
Memberships and donations received					26,612	167,952	72,821
Balance	11,372,355		11,358,692		11,372,355	11,358,692	10,823,463
Patronage Capital [Member]
Balance		148,355,246		149,543,952	148,355,246	149,543,952	144,228,221
Assignable margins					5,525,507	5,573,262	5,410,009
Retirement of capital credits					(48,079)	(6,761,968)	(94,278)
Unclaimed capital credit retirements					0	0	0
Memberships and donations received					0	0	0
Balance	$ 153,832,674		$ 148,355,246		$ 153,832,674	$ 148,355,246	$ 149,543,952