Bank subsidiary (Details 6) (USD $)	12 Months Ended
	Dec. 31, 2011 grade D	Dec. 31, 2010	Dec. 31, 2009
Derivative instrument
Standby, commercial and banker's acceptance letters of credit	$ 10,800,000	$ 16,300,000
Undrawn consumer lines of credit, including credit cards	943,100,000	856,700,000
Undrawn commercial loans including lines of credit	289,300,000	263,400,000
Real estate loans for investors	1,000,000,000	800,000,000	600,000,000
Loans pledged as collateral to secure advances from the FHLB of Seattle	1,100,000,000	1,400,000,000
Loans to directors, executive directors, affiliates and any related interest of such individuals	62,100,000	60,900,000
Increase in loans to directors, executive officers and related interests	1,200,000
New loans and lines of credit to executive directors	15,900,000
Lines of credit closed and repaid	14,700,000
Loan balances, related interests of individuals who are directors	56,400,000	52,500,000
Categorization of loan grades considered special mention grades	7
Categorization of loan grades considered substandard grades	8
Categorization of loan grades considered doubtful grades	9
Categorization of loan grades considered loss grades	10
Residential real estate
Period of all residential real estate loans in delinquency (in days)	180
Minimum
Derivative instrument
Categorization of loan grades considered pass grades	1
Period of unsecured consumer loans charged-off based on delinquency status (in days)	120
Maximum
Derivative instrument
Categorization of loan grades considered pass grades	6
Period of unsecured consumer loans charged-off based on delinquency status (in days)	180
Forward sale contracts | Not designated
Derivative instrument
Notional amount	$ 44,900,000	$ 21,900,000