Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Assets
Cash and cash equivalents	$ 236,346	$ 270,265
Accounts receivable and unbilled revenues, net	306,760	344,322
Available-for-sale investment and mortgage-related securities	631,063	624,331
Investment in stock of Federal Home Loan Bank of Seattle	97,764	97,764
Loans receivable held for investment, net	3,672,401	3,642,818
Loans held for sale, at lower of cost or fair value	14,657	9,601
Property, plant and equipment, net of accumulated depreciation of $2,061,649 in 2012 and $2,049,821 in 2011	3,375,654	3,334,501
Regulatory assets	677,674	669,389
Other	538,443	517,550
Goodwill	82,190	82,190
Total assets	9,632,952	9,592,731
Liabilities
Accounts payable	183,733	216,176
Interest and dividends payable	23,778	25,041
Deposit liabilities	4,125,204	4,070,032
Short-term borrowings-other than bank	156,288	68,821
Other bank borrowings	232,843	233,229
Long-term debt, net-other than bank	1,282,602	1,340,070
Deferred income taxes	375,510	354,051
Regulatory liabilities	316,560	315,466
Contributions in aid of construction	378,039	356,203
Retirement benefits liability	513,187	530,410
Other	456,817	516,990
Total liabilities	8,044,561	8,026,489
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: 96,541,143 shares in 2012 and 96,038,328 shares in 2011	1,362,880	1,349,446
Retained earnings	210,044	201,640
Accumulated other comprehensive loss, net of tax benefits	(18,826)	(19,137)
Total shareholders' equity	1,554,098	1,531,949
Total liabilities and shareholders' equity	$ 9,632,952	$ 9,592,731