Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Operating Activities:
Net income	$ 84,779	$ 160,034
Non-cash items included in net income:
Depreciation and amortization	109,522	102,899
Provision for deferred income taxes	12,381	111,335
Power and natural gas cost amortizations (deferrals), net	10,004	(17,956)
Amortization of debt expense	2,651	2,799
Amortization of investment in exchange power	1,838	1,838
Stock-based compensation expense	5,263	6,261
Equity-related AFUDC	(5,891)	(6,426)
Pension and other postretirement benefit expense	28,179	17,381
Amortization of Spokane Energy contract	10,023	9,214
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax	(710)	(161,100)
Other	(717)	14,568
Contributions to defined benefit pension plan	(12,000)	(32,000)
Changes in working capital components:
Accounts and notes receivable	49,524	64,761
Materials and supplies, fuel stock and natural gas stored	6,621	(22,979)
Increase (Decrease) in Deposit Assets	(9,917)	5,978
Increase (Decrease) in Income Taxes Receivable	43,266	(645)
Other current assets	3,408	(1,886)
Accounts payable	(32,378)	(22,450)
Increase (Decrease) in Income Taxes Payable	158	6,885
Other current liabilities	5,240	27,203
Net cash provided by operating activities	311,244	265,714
Investing Activities:
Utility property capital expenditures (excluding equity-related AFUDC)	(272,801)	(229,764)
Other capital expenditures	(852)	(6,316)
Federal grant payments received	2,752	2,191
Payments to Acquire Businesses, Net of Cash Acquired	(95)	15,007
Decrease (increase) In Money Market Funds Held For Clients	0	(18,931)
Payments to Acquire Available-for-sale Securities	0	(12,267)
Sale and maturity of securities available for sale	0	14,612
Proceeds from Divestiture of Businesses, Net of Cash Divested	0	229,903
Other	(106)	(1,194)
Net cash used in investing activities	(271,102)	(6,759)
Financing Activities:
Net increase (decrease) in short-term borrowings	25,000	(136,000)
Repayment of borrowings from Ecova line of credit	0	(46,000)
Proceeds from Issuance of Long-term Debt	0	75,000
Redemption and maturity of long-term debt	(2,174)	(39,367)
Maturity of nonrecourse long-term debt of Spokane Energy	(1,431)	(12,172)
Payments for (Proceeds from) Derivative Instrument, Financing Activities	(9,326)	0
Issuance of common stock	1,397	3,425
Payments for Repurchase of Common Stock	(2,920)	(60,963)
Cash dividends paid	(61,828)	(58,552)
Increase in client fund obligations	0	16,216
Payments to Noncontrolling Interests	0	(54,179)
Payments for Repurchase of Redeemable Noncontrolling Interest	0	(20,871)
Other	(1,689)	2,325
Net cash used in financing activities	(52,971)	(331,138)
Net decrease in cash and cash equivalents	(12,829)	(72,183)
Cash and cash equivalents at beginning of period	22,143	82,574
Cash and cash equivalents at end of period	$ 9,314	$ 10,391