CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
OPERATING ACTIVITIES:
Net Income	$ 39,709	$ 58,440
Items not affecting cash:
Depreciation	79,364	75,562
Amortization of debt issue costs, discount and deferred hedge gain	273	914
Amortization of restricted stock	2,199	1,649
Equity portion of allowance for funds used during construction	(3,311)	(960)
(Loss) gain on disposition of assets	(232)	850
Deferred income taxes	21,663	31,310
Mountain States Transmission Intertie impairment	24,039	0
Changes in current assets and liabilities:
Restricted cash	4,731	1,188
Accounts receivable	37,688	36,192
Inventories	156	(21,346)
Other current assets	(712)	(1,896)
Accounts payable	(9,604)	(12,808)
Accrued expenses	29,139	37,018
Regulatory assets	(3,266)	5,539
Regulatory liabilities	10,573	2,663
Other noncurrent assets	(13,400)	(3,451)
Other noncurrent liabilities	3,619	(359)
Cash provided by operating activities	222,628	210,505
INVESTING ACTIVITIES:
Property, plant, and equipment additions	(157,859)	(124,484)
Asset acquisition	(18,384)	0
Proceeds from sale of assets	262	209
Cash used in investing activities	(175,981)	(124,275)
FINANCING ACTIVITIES:
Treasury stock activity	(557)	169
Proceeds from issuance of common stock, net	28,477	0
Dividends on common stock	(40,584)	(38,930)
Issuance of long-term debt	150,000	0
Repayments on long-term debt	(3,871)	(6,586)
Line of credit borrowings	0	80,000
Line of credit repayments	0	(233,000)
(Repayments) issuances of short-term borrowings, net	(166,934)	112,993
Financing costs	(910)	(1,116)
Cash used in financing activities	(34,379)	(86,470)
Increase (Decrease) in Cash and Cash Equivalents	12,268	(240)
Cash and Cash Equivalents, beginning of period	5,928	6,234
Cash and Cash Equivalents, end of period	18,196	5,994
Cash paid during the period for:
Income taxes	1,944	18
Interest	34,416	28,950
Significant non-cash transactions:
Capital expenditures included in accounts payable and accrued expenses	$ 13,292	$ 4,314