Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Escrow receivable included in investing activities	$ 13,567	$ 0
Operating Activities:
Net income	149,563	68,831
Non-cash items included in net income:
Depreciation and amortization	68,543	64,890
Provision for deferred income taxes	(24,161)	1,404
Power and natural gas cost amortizations (deferrals), net	(10,032)	(430)
Amortization of debt expense	1,889	1,895
Amortization of investment in exchange power	1,225	1,225
Stock-based compensation expense	4,838	3,080
Equity-related AFUDC	(4,237)	(2,746)
Pension and other postretirement benefit expense	11,585	21,478
Amortization of Spokane Energy contract	6,078	5,587
Other Asset Impairment Charges	0	2,534
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax	(161,100)	0
Other	8,778	3,893
Contributions to defined benefit pension plan	(21,500)	(29,340)
Changes in working capital components:
Accounts and notes receivable	59,086	43,443
Materials and supplies, fuel stock and natural gas stored	(4,491)	2,133
Other current assets	12,263	(11,365)
Accounts payable	(34,025)	(27,106)
Increase (Decrease) in Income Taxes Payable	97,617	10,287
Other current liabilities	13,747	(1,090)
Net cash provided by operating activities	223,988	155,795
Investing Activities:
Utility property capital expenditures (excluding equity-related AFUDC)	(136,514)	(145,344)
Other capital expenditures	(6,122)	(1,344)
Federal grant payments received	1,729	2,297
Payments to Acquire Businesses, Gross	4,697	0
Decrease (increase) In Money Market Funds Held For Clients	(18,931)	10,675
Purchase of securities available for sale	(12,267)	(31,949)
Sale and maturity of securities available for sale	14,612	15,130
Proceeds from Divestiture of Businesses, Net of Cash Divested	229,903	0
Other	(475)	(4,369)
Net cash provided by (used in) investing activities	67,238	(154,904)
Financing Activities:
Net increase (decrease) in short-term borrowings	(19,500)	43,500
Borrowings from Ecova line of credit	0	3,000
Repayment of borrowings from Ecova line of credit	(46,000)	(5,000)
Redemption and maturity of long-term debt	(149)	(359)
Maturity of nonrecourse long-term debt of Spokane Energy	(8,026)	(7,329)
Payments for (Proceeds from) Derivative Instrument, Financing Activities	0	2,901
Issuance of common stock	1,980	3,017
Cash dividends paid	(38,327)	(36,667)
Increase in client fund obligations	16,216	6,220
Payments to Noncontrolling Interests	(54,179)	0
Payments for Repurchase of Redeemable Noncontrolling Interest	(20,871)	0
Other	3,023	(227)
Net cash provided by (used in) financing activities	(165,833)	9,056
Net increase in cash and cash equivalents	125,393	9,947
Cash and cash equivalents at beginning of period	82,574	75,464
Cash and cash equivalents at end of period	207,967	85,411
Cash paid during the year:
Interest	36,137	36,960
Income taxes	1,509	29,005
Non-cash financing and investing activities:
Accounts payable for capital expenditures	9,967	2,860
Redeemable noncontrolling interests	$ (15,873)	$ 2,931