Fair value measurements (Details 2) (USD $)	Jun. 30, 2013	Dec. 31, 2012
Financial liabilities
Short-term borrowings-other than bank	$ 125,786,000	$ 83,693,000
Other bank borrowings	187,884,000	195,926,000
Carrying or notional amount
Financial assets
Money market funds	10,000	10,000
Available-for-sale investment and mortgage-related securities	560,172,000	671,358,000
Investment in stock of Federal Home Loan Bank of Seattle	94,281,000	96,022,000
Loans receivable, net	3,946,703,000	3,763,238,000
Derivative assets	54,192,000
Financial liabilities
Deposit liabilities	4,276,243,000	4,229,916,000
Short-term borrowings-other than bank	125,786,000	83,693,000
Other bank borrowings	187,884,000	195,926,000
Long-term debt, net-other than bank	1,422,877,000	1,422,872,000
Derivative liabilities	19,350,000
Carrying or notional amount | American Savings Bank (ASB)
Financial liabilities
Loan commitments and unused lines and letters of credit	1,600,000,000	1,500,000,000
Notional amount of loans serviced	1,300,000,000	1,300,000,000
Estimated fair value
Financial assets
Money market funds	10,000	10,000
Available-for-sale investment and mortgage-related securities	560,172,000	671,358,000
Investment in stock of Federal Home Loan Bank of Seattle	94,281,000	96,022,000
Loans receivable, net	4,075,387,000	3,957,752,000
Derivative assets	1,163,000
Financial liabilities
Deposit liabilities	4,279,284,000	4,235,527,000
Short-term borrowings-other than bank	125,786,000	83,693,000
Other bank borrowings	200,813,000	212,163,000
Long-term debt, net-other than bank	1,450,844,000	1,481,004,000
Derivative liabilities	525,000
Estimated fair value | Level 1
Financial assets
Derivative assets	625,000
Estimated fair value | Level 2
Financial assets
Money market funds	10,000	10,000
Available-for-sale investment and mortgage-related securities	560,172,000	671,358,000
Investment in stock of Federal Home Loan Bank of Seattle	94,281,000	96,022,000
Derivative assets	538,000
Financial liabilities
Deposit liabilities	4,279,284,000	4,235,527,000
Short-term borrowings-other than bank	125,786,000	83,693,000
Other bank borrowings	200,813,000	212,163,000
Long-term debt, net-other than bank	1,450,844,000	1,481,004,000
Derivative liabilities	525,000
Estimated fair value | Level 3
Financial assets
Loans receivable, net	4,075,387,000	3,957,752,000
Estimated fair value | American Savings Bank (ASB)
Financial liabilities
Loan commitments and unused lines and letters of credit	100,000	1,200,000
Servicing rights on loans	$ 14,000,000	$ 11,900,000