Business Combination (Details) (USD $)	3 Months Ended		6 Months Ended					1 Months Ended	3 Months Ended	6 Months Ended				0 Months Ended	3 Months Ended	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Mar. 31, 2012	Feb. 29, 2012	Dec. 31, 2011	Mar. 31, 2012 First Independent Bank [Member]	Jun. 30, 2012 First Independent Bank [Member]	Jun. 30, 2012 First Independent Bank [Member]	Feb. 29, 2012 First Independent Bank [Member] Branches Installments	Jun. 30, 2012 Minimum [Member] First Independent Bank [Member]	Jun. 30, 2012 Maximum [Member] First Independent Bank [Member]	Feb. 29, 2012 Evidence of credit deterioration [Member]	Jun. 30, 2012 Evidence of credit deterioration [Member]	Jun. 30, 2012 Evidence of credit deterioration [Member]	Jun. 30, 2012 No Evidence of credit deterioration [Member]	Feb. 29, 2012 No Evidence of credit deterioration [Member]
Business Acquisition, Cost of Acquired Entity, Purchase Price [Abstract]
Net purchase price											$ 40,600,000
Cash paid											28,900,000
Contingent consideration fair value	13,292,000		13,292,000		11,779,000		0		13,300,000	13,300,000	11,700,000
Number of installments payable											2
First installment										12 months
Second installment										18 months
Potential cash payment range												0	17,000,000
Business Acquisition, Purchase Price Allocation, Noncurrent Assets [Abstract]
Additional branches acquired in Portland/Vancouver market											14
Cash and cash equivalents						150,045,000
Investments and MBS						187,465,000
Loans receivable, net						349,990,000
Core deposit intangible						11,974,000
Fixed assets						4,038,000
Other assets						10,886,000
Total assets acquired						736,975,000
Deposits						695,919,000
Other Liabilties						409,000
Total liabilities assumed						696,328,000
Net assets acquired						40,647,000
Business Acquisition, Pro Forma Information [Abstract]
Net interest income	78,910,000	82,633,000	159,744,000	164,716,000				11,100,000	7,859,000
Noninterest income	44,741,000	36,628,000	77,333,000	69,031,000				2,181,000	1,678,000
Net income	320,886,000	10,368,000	338,391,000	20,406,000				6,008,000	3,901,000
Earnigns per share - basic	$ 5.17	$ 0.17	$ 5.45	$ 0.33				$ 0.10	$ 0.06
Earnings per share - diluted	$ 5.13	$ 0.17	$ 5.40	$ 0.33				$ 0.10	$ 0.06
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period [Abstract]
Contractual cash flows														24,408,000
Expected prepayments and credit losses														7,220,000
Expected cash flows														17,188,000
Present value of expected cash flows														(15,265,000)
Certain Loans Acquired in Transfer Not Accounted for as Held-to-maturity Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Beginning Balance															1,909,000	0
Additions															0	1,923,000
Accretable yield														1,923,000	308,000	322,000
Reclassifications	730,000		730,000
Ending Balance															2,331,000	2,331,000
Loans Acquired, Not Accounted for as Debt Securities, Held-to-maturity Category [Abstract]
Unpaid principal of impaired loans	20,400,000		20,400,000
Carrying amount of purchase impaired loans	13,300,000		13,300,000
Unpaid principal balance and contractual interest																		403,800,000
Cash flows not expected to be collected																	12,700,000
Cash flow discounted on loans																		21,800,000
Investment Income, Net, Amortization of Discount and Premium [Abstract]
Remainder of 2012	4,022,000		4,022,000
2013	4,210,000		4,210,000
2014	2,796,000		2,796,000
2015	1,724,000		1,724,000
2016	1,031,000		1,031,000
2017	679,000		679,000
Goodwill	$ 22,577,000		$ 22,577,000			$ 22,577,000	$ 0