Securities (Tables)

12 Months Ended

Dec. 31, 2012

Available-for-sale Securities [Abstract]

Securities Available for Sale

The following table summarizes the amortized cost, gross unrealized gains and losses and the resulting fair value of securities available for sale:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
December 31, 2012	(in thousands)
U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations	$	561,076	$	16,719	$	(5,426	)	$	572,369
State and municipal securities	265,070		20,893		(388		)	285,575
U.S. government agency and government-sponsored enterprise securities	120,085		851		(435		)	120,501
U.S. government securities	19,804		39		(15		)	19,828
Other securities	3,324		104		(36		)	3,392
Total	$	969,359	$	38,606	$	(6,300	)	$	1,001,665
December 31, 2011
U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations	$	678,631	$	19,323	$	(2,000	)	$	695,954
State and municipal securities	263,075		22,746		(58		)	285,763
U.S. government agency and government-sponsored enterprise securities	42,558		505		—			43,063
Other securities	3,296		64		(30		)	3,330
Total	$	987,560	$	42,638	$	(2,088	)	$	1,028,110

Schedule of Contractual Maturities of Investment Securities Available for Sale

The following table summarizes the amortized cost and fair value of securities available for sale by contractual maturity groups:

	December 31, 2012
	Amortized Cost		Fair Value
	(in thousands)
Due within one year	$	25,062	$	25,440
Due after one year through five years	127,971		131,704
Due after five years through ten years	209,031		215,390
Due after ten years	603,971		625,739
Other securities with no stated maturity	$	3,324	$	3,392
Total investment securities available-for-sale	$	969,359	$	1,001,665

Carrying Value of Securities Pledged As Collateral

The following table summarizes, as of December 31, 2012 and 2011, the carrying value of securities pledged as collateral to secure public deposits, borrowings and other purposes as permitted or required by law:

	December 31, 2012		December 31, 2011
	(in thousands)
To Washington and Oregon State to secure public deposits	$	281,006	$	225,345
To Federal Home Loan Bank to secure advances	—		91,097
To Federal Reserve Bank to secure borrowings	47,634		56,347
Other securities pledged	46,090		47,454
Total securities pledged as collateral	$	374,730	$	420,243

Summary of Gross Unrealized Losses and Fair Value of the Investments with Unrealized Losses

The following tables show the gross unrealized losses and fair value of the Company’s investments with unrealized losses that are not deemed to be other-than-temporarily impaired, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position at December 31, 2012 and 2011:

	Less than 12 Months					12 Months or More					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
December 31, 2012	(in thousands)
U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations	$	167,739	$	(5,090	)	$	12,204	$	(336	)	$	179,943	(5,426		)
State and municipal securities	20,413		(383		)	210		(5		)	20,623		(388		)
U.S. government agency and government-sponsored enterprise securities	56,600		(435		)	—		—			56,600		(435		)
U.S. government securities	9,914		(15		)	—		—			9,914		(15		)
Other securities	—		—			964		(36		)	964		(36		)
Total	$	254,666	$	(5,923	)	$	13,378	$	(377	)	$	268,044	$	(6,300	)
December 31, 2011
U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations	$	238,875	$	(1,999	)	$	196	$	(1	)	$	239,071	$	(2,000	)
State and municipal securities	3,820		(24		)	950		(34		)	4,770		(58		)
Other securities	—		—			970		(30		)	970		(30		)
Total	$	242,695	$	(2,023	)	$	2,116	$	(65	)	$	244,811	$	(2,088	)