Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Assets
Cash and cash equivalents	$ 207,549	$ 270,265
Accounts receivable and unbilled revenues, net	386,750	344,322
Available-for-sale investment and mortgage-related securities	639,112	624,331
Investment in stock of Federal Home Loan Bank of Seattle	97,764	97,764
Loans receivable held for investment, net	3,695,474	3,642,818
Loans held for sale, at lower of cost or fair value	11,915	9,601
Property, plant and equipment, net of accumulated depreciation of $2,086,098 in 2012 and $2,049,821 in 2011	3,436,021	3,334,501
Regulatory assets	698,448	669,389
Other	566,734	519,296
Goodwill	82,190	82,190
Total assets	9,821,957	9,594,477
Liabilities
Accounts payable	231,871	216,176
Interest and dividends payable	24,897	25,041
Deposit liabilities	4,136,741	4,070,032
Short-term borrowings-other than bank	96,240	68,821
Other bank borrowings	218,673	233,229
Long-term debt, net-other than bank	1,429,653	1,340,070
Deferred income taxes	396,806	354,051
Regulatory liabilities	317,958	315,466
Contributions in aid of construction	381,206	356,203
Retirement benefits liability	497,687	530,410
Other	480,156	521,979
Total liabilities	8,211,888	8,031,478
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: 97,023,148 shares in 2012 and 96,038,328 shares in 2011	1,377,426	1,349,446
Retained earnings	215,626	198,397
Accumulated other comprehensive loss, net of tax benefits	(17,276)	(19,137)
Total shareholders' equity	1,575,776	1,528,706
Total liabilities and shareholders' equity	$ 9,821,957	$ 9,594,477