Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Operating Activities:
Net income	$ 80,762	$ 62,707
Non-cash items included in net income:
Depreciation and amortization	98,793	93,293
Provision for deferred income taxes	16,512	18,380
Power and natural gas cost amortizations (deferrals), net	(10,149)	10,418
Amortization of debt expense	2,841	2,876
Amortization of investment in exchange power	1,838	1,838
Stock-based compensation expense	4,718	4,539
Equity-related AFUDC	(4,341)	(2,875)
Pension and other postretirement benefit expense	31,894	29,785
Amortization of Spokane Energy contract	8,470	7,786
Write-off of Reardan wind generation capitalized costs	2,534	0
Other	6,889	8,911
Contributions to defined benefit pension plan	(44,000)	(44,000)
Changes in working capital components:
Accounts and notes receivable	50,681	61,106
Materials and supplies, fuel stock and natural gas stored	(9,388)	941
Other current assets	(23,165)	7,209
Accounts payable	(23,756)	(10,783)
Other current liabilities	11,269	5,277
Net cash provided by operating activities	202,402	257,408
Investing Activities:
Utility property capital expenditures (excluding equity-related AFUDC)	(220,712)	(178,440)
Other capital expenditures	(1,725)	(3,908)
Federal grant payments received	2,631	5,902
Cash paid by subsidiaries for acquisitions, net of cash received	0	(50,310)
Decrease (increase) In Money Market Funds Held For Clients	11,723	(9,599)
Purchase of securities available for sale	(35,949)	(88,843)
Sale and maturity of securities available for sale	16,955	103,545
Other	(6,481)	(7,412)
Net cash used in investing activities	(233,558)	(229,065)
Financing Activities:
Net increase in short-term borrowings	14,000	21,000
Borrowings from Ecova line of credit	3,000	28,000
Repayment of borrowings from Ecova line of credit	(7,000)	(5,000)
Proceeds from Issuance of Long-term Debt	90,000	0
Redemption and maturity of long-term debt	(415)	(11,363)
Maturity of nonrecourse long-term debt of Spokane Energy	(11,115)	(10,153)
Long-term debt and short-term borrowing issuance costs	(471)	(177)
Cash received (paid) for settlement of interest rate swap agreements	2,901	(18,547)
Issuance of common stock	4,479	28,699
Cash dividends paid	(54,963)	(51,215)
Purchase of subsidiary noncontrolling interest	(379)	(917)
Increase (decrease) in client fund obligations	7,375	(5,220)
Issuance of subsidiary noncontrolling interest	0	3,714
Other	259	1,126
Net cash provided by (used in) financing activities	47,671	(20,053)
Net cash provided by (used in) financing activities	16,515	8,290
Cash and cash equivalents at beginning of period	75,464	74,662
Cash and cash equivalents at end of period	91,979	82,952
Cash paid during the year:
Interest	45,633	43,487
Income taxes	33,522	12,527
Non-cash financing and investing activities:
Accounts payable for capital expenditures	4,313	3,556
Redeemable noncontrolling interests	$ 3,246	$ (8,274)