CONSOLIDATED STATEMENTS OF CAPITALIZATION (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Long-term debt:
Total Secured Long-term, net	$ 5,670,449	$ 5,432,503
Unsecured bank term loans:
Notes payable: variable at 1.46% through January 8, 2013, due April 2014	260,000	260,000
Total long-term debt	5,930,449	5,692,503
Obligations under capital leases	161,249	191,900
Obligation under Rocky Mountain transactions	14,392	132,048
Patronage capital and membership fees	673,009	633,689
Accumulated other comprehensive margin	903	618
Subtotal	6,780,002	6,650,758
Less: long-term debt and capital leases due within one year	(168,393)	(172,818)
Less: unamortized bond discounts on long-term debt	(3,232)	(1,879)
Total capitalization	6,608,377	6,476,061
Federal Financing Bank | Mortgage notes payable to the Federal Financing Bank at interest rates varying from 2.20% to 8.43% (average rate of 4.86% at December 31, 2012) due in quarterly installments through 2043
Long-term debt:
Debt Instrument Principal Outstanding	2,115,640	2,125,149
National Rural Utilities Cooperative Finance Corporation | Mortgage notes payable to National Rural Utilities Cooperative Finance Corporation at interest rates varying from 3.25% to 4.90% (average rate of 4.19% at December 31, 2012) due in quarterly installments through 2020
Long-term debt:
Debt Instrument Principal Outstanding	6,659	7,388
Public | Mortgage bonds payable: Series 2006 First Mortgage Bonds, 5.534%, due 2031 through 2035
Long-term debt:
Debt Instrument Principal Outstanding	300,000	300,000
Public | Mortgage bonds payable: Series 2007 First Mortgage Bonds, 6.191%, due 2024 through 2031
Long-term debt:
Debt Instrument Principal Outstanding	500,000	500,000
Public | Mortgage bonds payable: Series 2009A First Mortgage Bonds, 6.10%, due 2019
Long-term debt:
Debt Instrument Principal Outstanding	350,000	350,000
Public | Mortgage bonds payable: Series 2009B First Mortgage Bonds, 5.95%, due 2039
Long-term debt:
Debt Instrument Principal Outstanding	400,000	400,000
Public | Mortgage bonds payable: Series 2009 Clean renewable energy bond, 1.81%, due 2024
Long-term debt:
Debt Instrument Principal Outstanding	12,124	13,134
Public | Mortgage bonds payable: Series 2010A First Mortgage Bonds, 5.375% due 2040
Long-term debt:
Debt Instrument Principal Outstanding	450,000	450,000
Public | Mortgage bonds payable: Series 2011A First Mortgage Bonds, 5.25% due 2050
Long-term debt:
Debt Instrument Principal Outstanding	300,000	300,000
Public | Mortgage bonds payable: Series 2012A First Mortgage Bonds, 4.20% due 2042
Long-term debt:
Debt Instrument Principal Outstanding	250,000
Georgia Development Authorities | Mortgage notes issued in connection with the sale of pollution control revenue bonds: Series 1992A Monroe County, Georgia: Serial bonds, fully redeemed January 2012
Long-term debt:
Debt Instrument Principal Outstanding		10,371
Georgia Development Authorities | Mortgage notes issued in connection with the sale of pollution control revenue bonds: Series 2003A Burke, Heard, Monroe and 2003B Burke Auction rate bonds, 0.32%, due 2024
Long-term debt:
Debt Instrument Principal Outstanding	95,230	95,230
Georgia Development Authorities | Mortgage notes issued in connection with the sale of pollution control revenue bonds: Series 2004 Burke and Monroe Auction rate bonds, 0.32%, due 2020
Long-term debt:
Debt Instrument Principal Outstanding	11,525	11,525
Georgia Development Authorities | Mortgage notes issued in connection with the sale of pollution control revenue bonds: Series 2005 Burke and Monroe Auction rate bonds, 0.32%, due 2040
Long-term debt:
Debt Instrument Principal Outstanding	15,865	15,865
Georgia Development Authorities | Mortgage notes issued in connection with the sale of pollution control revenue bonds: Series 2008A through 2008C Burke Fixed rate bonds, 5.30% to 5.70%, due 2032 through 2043
Long-term debt:
Debt Instrument Principal Outstanding	255,035	255,035
Georgia Development Authorities | Mortgage notes issued in connection with the sale of pollution control revenue bonds: Series 2008E Burke Fixed rate bonds, 7.00%, due 2020 through 2023
Long-term debt:
Debt Instrument Principal Outstanding	144,750	144,750
Georgia Development Authorities | Mortgage notes issued in connection with the sale of pollution control revenue bonds: Series 2008G Burke Term rate bonds, 0.90% through February 28, 2013, due 2039
Long-term debt:
Debt Instrument Principal Outstanding	22,325	22,325
Georgia Development Authorities | Mortgage notes issued in connection with the sale of pollution control revenue bonds: Series 2009A Heard and Monroe, and 2009B Monroe Weekly rate bonds, 0.15%, due 2030 through 2038
Long-term debt:
Debt Instrument Principal Outstanding	112,055	112,055
Georgia Development Authorities | Mortgage notes issued Series 2010A Burke and Monroe, and 2010B Burke Weekly rate bonds, 0.13% to 0.15%, due 2036 through 2037
Long-term debt:
Debt Instrument Principal Outstanding	133,550	133,550
Georgia Development Authorities | Mortgage notes issued Series 2011A Appling, Burke and Monroe Term rate bonds, 2.50% through February 28, 2013, due 2038 through 2040
Long-term debt:
Debt Instrument Principal Outstanding	180,380	180,380
Georgia Development Authorities | Mortgage notes issued Series 2012A Monroe, Term rate bonds, 0.90% through February 28, 2013, due 2039
Long-term debt:
Debt Instrument Principal Outstanding	10,055
CoBank | ACB notes payable: Transmission mortgage notes payable: variable at 2.09% to 3.25% through January 30, 2013, due in bimonthly installments through September 1, 2019
Long-term debt:
Debt Instrument Principal Outstanding	$ 5,256	$ 5,746