Long-Term Debt (Details 3) (USD $)	12 Months Ended			1 Months Ended														12 Months Ended			12 Months Ended		12 Months Ended		0 Months Ended
	May 31, 2014	May 31, 2013	May 31, 2012	Jun. 30, 2013 2.35% Bonds due 2020	Nov. 30, 2013 3.40% Bonds due 2023	Jan. 31, 2014 1.10% Bonds due 2017	Jan. 31, 2014 2.15% Bonds due 2019	Oct. 31, 2012 8 percent medium-term notes, Series C, due 2032	Oct. 31, 2012 4.023% collateral trust bonds due 2032	May 31, 2014 Collateral trust bonds		May 31, 2013 Collateral trust bonds		May 31, 2014 Unsecured notes payable		May 31, 2013 Unsecured notes payable		May 31, 2014 Unsecured notes payable RUS	May 31, 2014 Unsecured notes payable Federal Financing Bank RUS	May 31, 2013 Unsecured notes payable Federal Financing Bank RUS	May 31, 2014 Committed loan facilities Federal Financing Bank	May 31, 2014 Committed loan facilities Federal Financing Bank Maximum	May 31, 2014 Committed loan facilities Federal Financing Bank Loan guarantees RUS	Nov. 21, 2013 Committed loan facilities Federal Financing Bank Loan guarantees RUS	May 23, 2014 Secured notes payable Federal Agricultural Mortgage Corporation	May 02, 2014 Secured notes payable Federal Agricultural Mortgage Corporation	May 31, 2014 Secured notes payable Federal Agricultural Mortgage Corporation	May 31, 2013 Secured notes payable Federal Agricultural Mortgage Corporation
Long-term debt
Amount of debt issued in exchange									$ 218,000,000
Stated interest rate (as a percent)				2.35%	3.40%	1.10%	2.15%	8.00%	4.023%
Amount of debt exchanged								209,000,000
Cash paid in exchange									91,000,000
Long-term debt before unamortized discount										5,852,711,000	[1]	4,639,372,000	[1]	4,315,167,000	[2]	3,709,074,000	[2]		4,299,000,000	3,674,000,000							1,668,000,000	1,542,000,000
Fee per year payable to RUS on the total amount borrowed (as a percent)																		0.30%
Available under committed loan facilities																						624,000,000
Amounts borrowed	0	395,724,000	0	400,000,000	400,000,000	300,000,000	300,000,000														625,000,000				91,000,000	60,000,000
Commitment to guarantee loan																								500,000,000
Maturity period																							20 years
Maximum borrowing capacity																											3,900,000,000
Debt outstanding with remaining maturity of less than one year classified as short-term debt	$ 1,422,000,000									$ 405,000,000											$ 15,000,000						$ 235,000,000	$ 741,000,000

[1] We are required to make mandatory sinking fund payments for these bonds on November 1 of each year through 2025 totaling $5 million to retire 95% percent of the principal amount before maturity. Collateral trust bond exclude $405 million and $1,505 million in bonds that were reclassified as short-term debt at May 31, 2014 and 2013, respectively.

[2] Unsecured notes payable exclude $19 million and $4 million, respectively, of unsecured notes payable that were reclassified as short-term debt at May 31, 2014 and 2013.