Bank subsidiary (Details 3) (USD $)	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010
Assets
Available-for-sale investment and mortgage-related securities	$ 639,112,000	$ 624,331,000
Investment in stock of Federal Home Loan Bank of Seattle	97,764,000	97,764,000
Loans receivable held for investment, net	3,695,474,000	3,642,818,000
Loans held for sale, at lower of cost or fair value	11,915,000	9,601,000
Other	566,734,000	519,296,000
Goodwill	82,190,000	82,190,000
Total assets	9,821,957,000	9,594,477,000
Liabilities and shareholders' equity
Other	480,156,000	521,979,000
Total liabilities	8,211,888,000	8,031,478,000
Common stock	1,377,426,000	1,349,446,000
Retained earnings	215,626,000	198,397,000		178,667,000
Accumulated other comprehensive loss, net of tax benefits	(17,276,000)	(19,137,000)
Total shareholders' equity	1,575,776,000	1,528,706,000	1,508,964,000	1,480,394,000
Total liabilities and shareholders' equity	9,821,957,000	9,594,477,000
Other assets
Premises and equipment, net	3,436,021,000	3,334,501,000
Total other assets	566,734,000	519,296,000
Other liabilities
Total other liabilities	480,156,000	521,979,000
American Savings Bank (ASB)
Assets
Cash and cash equivalents	201,193,000	219,678,000
Available-for-sale investment and mortgage-related securities	639,112,000	624,331,000
Investment in stock of Federal Home Loan Bank of Seattle	97,764,000	97,764,000
Loans receivable held for investment	3,734,937,000	3,680,724,000
Allowance for loan losses	(39,463,000)	(37,906,000)
Loans receivable held for investment, net	3,695,474,000	3,642,818,000
Loans held for sale, at lower of cost or fair value	11,915,000	9,601,000
Other	236,547,000	233,592,000
Goodwill	82,190,000	82,190,000
Total assets	4,964,195,000	4,909,974,000
Liabilities and shareholders' equity
Deposit liabilities-noninterest-bearing	1,076,579,000	993,828,000
Deposit liabilities-interest-bearing	3,060,162,000	3,076,204,000
Other borrowings	218,673,000	233,229,000
Other	107,902,000	118,078,000
Total liabilities	4,463,316,000	4,421,339,000
Common stock	332,769,000	331,880,000
Retained earnings	176,192,000	166,126,000
Accumulated other comprehensive loss, net of tax benefits	(8,082,000)	(9,371,000)
Total shareholders' equity	500,879,000	488,635,000
Total liabilities and shareholders' equity	4,964,195,000	4,909,974,000
Other assets
Bank-owned life insurance	123,563,000	121,470,000
Premises and equipment, net	53,521,000	52,940,000
Prepaid expenses	15,423,000	15,297,000
Accrued interest receivable	14,084,000	14,190,000
Mortgage-servicing rights	8,818,000	8,227,000
Real estate acquired in settlement of loans, net	6,210,000	7,260,000
Other	14,928,000	14,208,000
Total other assets	236,547,000	233,592,000
Other liabilities
Accrued expenses	12,928,000	21,216,000
Federal and state income taxes payable	35,052,000	35,002,000
Cashier's checks	23,094,000	22,802,000
Advance payments by borrowers	9,975,000	10,100,000
Other	26,853,000	28,958,000
Total other liabilities	107,902,000	118,078,000
Balance Sheet related disclosures
Securities sold under agreements to repurchase	169,000,000	183,000,000
Advances from Federal Home Loan Bank	50,000,000	50,000,000
Loan commitments and unused lines and letters of credit	1,400,000,000
Commitments to borrowers whose loan terms are modified under troubled debt restructuring	$ 3,000,000