Equity (Details) (USD $)	12 Months Ended								1 Months Ended	12 Months Ended	1 Months Ended												1 Months Ended
	May 31, 2014	May 31, 2013	May 31, 2012	May 31, 2014 Patronage capital allocated	May 31, 2013 Patronage capital allocated	May 31, 2012 Patronage capital allocated	May 31, 2014 CFC reserve	May 31, 2014 CFC Cooperative educational fund Minimum	May 31, 2013 CFC Cooperative educational fund Authorized Allocations	May 31, 2014 CFC Patronage capital allocated	Jul. 31, 2013 CFC Patronage capital allocated Authorized Allocations	Jul. 31, 2012 CFC Patronage capital allocated Authorized Allocations	Jul. 31, 2013 CFC Members' capital reserve	Dec. 31, 2013 RTFC	May 31, 2014 RTFC	Jan. 31, 2014 RTFC	May 31, 2014 RTFC Authorized Allocations Minimum	Dec. 31, 2013 RTFC Cooperative educational fund	May 31, 2014 RTFC Cooperative educational fund Minimum	Dec. 31, 2013 RTFC Members' capital reserve	May 31, 2014 NCSC	May 31, 2014 NCSC Cooperative educational fund Minimum	Jan. 31, 2014 Cash Distribution [Member] RTFC	Dec. 31, 2013 Cash Distribution [Member] RTFC	Dec. 31, 2013 Redeemable Certificates [Member] RTFC
Equity
Minimum percentage of paid-in-capital required to be maintained under District of Columbia cooperative law	50.00%														50.00%						50.00%
General reserve required to be maintained as a percentage of membership fees collected							50.00%
Minimum percentage of net earnings to be allocated to cooperative education fund as per bylaws of the entity								0.25%										1.00%	1.00%	99.00%		0.25%
Number of additional board-approved reserves							1
Percentage of prior year's allocated patronage capital required to be retired										50.00%
Percentage of prior year's allocated patronage capital required to be held										50.00%
Period for which prior year's allocated patronage capital is required to be held										25 years
Allocation of net earnings									$ 1,000,000		$ 79,000,000	$ 81,000,000	$ 75,000,000	$ (2,000,000)
Members' Capital											138,000,000
Retirement/allocation of net earnings authorized	$ (40,965,000)	$ (36,599,000)	$ (46,265,000)	$ (40,565,000)	$ (36,234,000)	$ (46,221,000)					$ (40,000,000)	$ (41,000,000)											$ 400,000	$ (400,000)	$ 1,600,000
Percentage of ownership by parent															100.00%						100.00%
Percentage of ownership by minority owners															100.00%						100.00%
Percentage of retirement of allocated net earnings in cash																20.00%	20.00%
Retirement of allocated net earnings, percentage											50.00%	50.00%