CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 84,998	$ 70,505
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	46,440	44,682
Recognition of and refund and collection of revenue accruals and deferrals - including accrued interest	18,116	46,676
Deferred income tax expense	31,421	35,191
Allowance for equity funds used during construction	(7,609)	(6,578)
Other	7,554	5,937
Changes in assets and liabilities, exclusive of changes shown separately:
Accounts receivable	(16,036)	(13,911)
Inventory	2,537	(2,283)
Other current assets	(1,602)	(4,711)
Accounts payable	969	(1,410)
Accrued payroll	(5,143)	(3,421)
Accrued interest	304	5,420
Accrued taxes	10,292	5,996
Other current liabilities	(2,012)	681
Other non-current assets and liabilities, net	(2,444)	624
Net cash provided by operating activities	167,785	183,398
CASH FLOWS FROM INVESTING ACTIVITIES
Expenditures for property, plant and equipment	(228,028)	(162,585)
Proceeds from sale of securities	3,809	14,576
Purchases of securities	(7,160)	(14,587)
Other	578	(78)
Net cash used in investing activities	(230,801)	(162,674)
CASH FLOWS FROM FINANCING ACTIVITIES
Issuance of long-term debt		90,000
Borrowings under revolving credit agreements	377,415	213,129
Repayments of revolving credit agreements	(308,775)	(279,985)
Issuance of common stock	15,025	1,165
Dividends on common stock	(34,189)	(32,121)
Refundable deposits from generators for transmission network upgrades	9,054	11,439
Repayment of refundable deposits from generators for transmission network upgrades	(4,876)	(16,778)
Other	(4,512)	(987)
Net cash provided by (used in) financing activities	49,142	(14,138)
NET (DECREASE)/INCREASE IN CASH AND CASH EQUIVALENTS	(13,874)	6,586
CASH AND CASH EQUIVALENTS - Beginning of period	95,109	74,853
CASH AND CASH EQUIVALENTS - End of period	$ 81,235	$ 81,439