CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:
Net margin	$ 41,480	$ 39,320	$ 37,737
Adjustments to reconcile net margin to net cash provided by operating activities:
Depreciation and amortization, including nuclear fuel	296,546	301,442	321,715
Accretion cost	22,900	19,554	18,249
Amortization of deferred gains	(1,788)	(45,952)	(5,660)
Allowance for equity funds used during construction	(2,397)	(2,879)	(2,904)
Deferred outage costs	(43,302)	(26,392)	(56,358)
Deferral of Hawk Road and Smith Energy Facilities effect on net margin	(35,662)	(16,280)	(9,681)
Gain on sale of investments	(24,962)	(10,784)	(14,915)
Regulatory deferral of costs associated with nuclear decommissioning	10,181	(710)	5,089
Other	(8,718)	(7,786)	(10,598)
Change in operating assets and liabilities:
Receivables	4,743	(17,465)	(8,456)
Inventories	(22,219)	(17,154)	(40,774)
Prepayments and other current assets	191	(355)	(2,146)
Accounts payable	(32,665)	(12,714)	8,617
Accrued interest	(456)	(32,457)	14,671
Accrued and withheld taxes	17,996	(16,237)	(6,362)
Other current liabilities	318	(412)	542
Member power bill prepayments	8,787	3,613	(10,177)
Total adjustments	189,493	117,032	200,852
Net cash provided by operating activities	230,973	156,352	238,589
Cash flows from investing activities:
Property additions	(628,216)	(646,486)	(839,503)
Plant acquisitions			(530,293)
Activity in nuclear decommissioning trust fund - Purchases	(568,979)	(657,638)	(1,068,979)
Activity in nuclear decommissioning trust fund - Proceeds	563,712	651,709	1,063,277
Activity in bond, reserve and construction funds - Purchases		2,719
(Increase) decrease in restricted cash and cash equivalents	(26,022)	34,574	(37,383)
(Increase) decrease in restricted short-term investments	(208,015)	42,005	(9,390)
Activity in other long-term investments - Purchases	(40,593)	(6,278)	(2,469)
Activity in other long-term investments - Proceeds	41,652	14,772	1,100
Activity on interest rate options - Purchases/Collateral returned	(187,190)	(208,850)	(100,000)
Activity on interest rate options - Collateral received	213,210	174,730	43,070
Other	6,626	(19,055)	(10,254)
Net cash used in investing activities	(833,815)	(617,798)	(1,490,824)
Cash flows from financing activities:
Long-term debt proceeds	888,857	366,008	1,163,593
Long-term debt payments	(351,273)	(164,938)	(288,722)
Increase in short-term borrowings	174,927	108,386	155,135
Other	(41)	6,884	(6,312)
Net cash provided by financing activities	712,470	316,340	1,023,694
Net increase (decrease) in cash and cash equivalents	109,628	(145,106)	(228,541)
Cash and cash equivalents at beginning of period	298,565	443,671	672,212
Cash and cash equivalents at end of period	408,193	298,565	443,671
Cash paid for -
Interest (net of amounts capitalized)	213,404	246,705	196,629
Supplemental disclosure of non-cash investing and financing activities:
Change in plant expenditures included in accounts payable	$ (3,473)	$ 32,657	$ (7,848)