Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
ASSETS
Cash and cash equivalents	$ 270,265	$ 330,651
Accounts receivable and unbilled revenues, net	344,322	266,996
Available-for-sale investment and mortgage-related securities	624,331	678,152
Investment in stock of Federal Home Loan Bank of Seattle	97,764	97,764
Loans receivable held for investment, net	3,642,818	3,489,880
Loans held for sale, at lower of cost or fair value	9,601	7,849
Property, plant and equipment, net
Land	66,152	66,002
Plant and equipment	5,177,453	5,034,211
Construction in progress	140,717	103,303
Property, plant and equipment, gross	5,384,322	5,203,516
Less - accumulated depreciation	(2,049,821)	(2,037,598)
Property, plant and equipment, net	3,334,501	3,165,918
Regulatory assets	669,389	478,330
Other	517,550	487,614
Goodwill	82,190	82,190
Total assets	9,592,731	9,085,344
Liabilities
Accounts payable	216,176	202,446
Interest and dividends payable	25,041	27,814
Deposit liabilities	4,070,032	3,975,372
Short-term borrowings-other than bank	68,821	24,923
Other bank borrowings	233,229	237,319
Long-term debt, net-other than bank	1,340,070	1,364,942
Deferred income taxes	354,051	278,958
Regulatory liabilities	315,466	296,797
Contributions in aid of construction	356,203	335,364
Retirement benefits liability	530,410	376,994
Other	516,990	446,485
Total liabilities	8,026,489	7,567,414
Preferred stock of subsidiaries - not subject to mandatory redemption	34,293	34,293
Commitments and contingencies (Notes 3 and 4)
Shareholders' equity
Preferred stock, no par value, authorized 10,000,000 shares; issued: none
Common stock, no par value, authorized 200,000,000 shares; issued and outstanding: 96,038,328 shares and 94,690,932 shares in 2011 and 2010, respectively	1,349,446	1,314,199
Retained earnings	201,640	181,910
Accumulated other comprehensive income (loss), net of taxes
Net unrealized gains on securities	9,886	3,532
Unrealized losses on derivatives	(996)	(1,169)
Retirement benefit plans	(28,027)	(14,835)
Accumulated other comprehensive loss, net of taxes	(19,137)	(12,472)
Total shareholders' equity	1,531,949	1,483,637
Total liabilities and shareholders' equity	$ 9,592,731	$ 9,085,344