CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities:
Net margin	$ 39,320	$ 37,737	$ 33,733
Adjustments to reconcile net margin to net cash provided by operating activities:
Depreciation and amortization, including nuclear fuel	301,442	321,715	250,723
Accretion cost	19,554	18,249	17,131
Amortization of deferred gains	(45,952)	(5,660)	(5,660)
Allowance for equity funds used during construction	(2,879)	(2,904)	(2,417)
Deferred outage costs	(26,392)	(56,358)	(25,911)
Deferral of Hawk Road and Smith Energy Facilities effect on net margin	(16,280)	(9,681)	13,849
Gain on sale of investments	(10,784)	(14,915)	(14,239)
Regulatory deferral of costs associated with nuclear decommissioning	(710)	5,089	5,480
Other	(7,786)	(10,598)	(9,022)
Change in operating assets and liabilities:
Receivables	(17,465)	(8,456)	(7,299)
Inventories	(17,154)	(40,774)	38,022
Prepayments and other current assets	(355)	(2,146)	(4,023)
Accounts payable	(12,714)	8,617	(729)
Accrued interest	(32,457)	14,671	25,488
Accrued and withheld taxes	(16,237)	(6,362)	2,307
Other current liabilities	(412)	542	791
Member power bill prepayments	3,613	(10,177)	(88,018)
Total adjustments	117,032	200,852	196,473
Net cash provided by operating activities	156,352	238,589	230,206
Cash flows from investing activities:
Property additions	(646,486)	(839,503)	(669,206)
Plant acquisitions		(530,293)
Activity in nuclear decommissioning trust fund - Purchases	(657,638)	(1,068,979)	(608,542)
Activity in nuclear decommissioning trust fund - Proceeds	651,709	1,063,277	603,600
Activity in bond, reserve and construction funds - Purchases	2,719
Decrease (increase) in restricted cash and cash equivalents	34,574	(37,383)	16,105
Decrease (increase) in restricted short-term investments	42,005	(9,390)	(16,696)
Activity in other long-term investments - Purchases	(6,278)	(2,469)	(6,822)
Activity in other long-term investments - Proceeds	14,772	1,100	18,524
Activity on interest rate options - Purchases/Collateral returned	(208,850)	(100,000)
Activity on interest rate options - Collateral received	174,730	43,070
Other	(19,055)	(10,254)	2,822
Net cash used in investing activities	(617,798)	(1,490,824)	(660,215)
Cash flows from financing activities:
Long-term debt proceeds	366,008	1,163,593	740,124
Long-term debt payments	(164,938)	(288,722)	(240,185)
Increase in short-term borrowings	108,386	155,135	22,325
Other	6,884	(6,312)	888
Net cash provided by financing activities	316,340	1,023,694	523,152
Net (decrease) increase in cash and cash equivalents	(145,106)	(228,541)	93,143
Cash and cash equivalents at beginning of period	443,671	672,212	579,069
Cash and cash equivalents at end of period	298,565	443,671	672,212
Cash paid for -
Interest (net of amounts capitalized)	246,705	196,629	187,958
Supplemental disclosure of non-cash investing and financing activities:
Change in plant expenditures included in accounts payable	$ 32,657	$ (7,848)	$ 138,898