Securities

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



(in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
September 30, 2011:
U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations	$	623,934	$	21,698	$	(906	)	$	644,726
State and municipal securities	256,343		20,189		(115		)	276,417
U.S. government and government-sponsored enterprise securities	70,857		523		—			71,380
Other securities	3,281		77		(27		)	3,331
Total	$	954,415	$	42,487	$	(1,048	)	$	995,854
December 31, 2010:
U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations	$	491,530	$	16,139	$	(1,027	)	$	506,642
State and municipal securities	249,117		7,247		(2,383		)	253,981
Other securities	3,281		—		(38		)	3,243
Total	$	743,928	$	23,386	$	(3,448	)	$	763,866

The scheduled contractual maturities of investment securities available for sale at September 30, 2011 are presented as follows:



	September 30, 2011
	Amortized Cost		Fair Value
	(in thousands)
Due within one year	$	43,868	$	44,136
Due after one year through five years	91,742		94,242
Due after five years through ten years	168,119		176,815
Due after ten years	647,405		677,330
Total investment securities available-for-sale	$	951,134	$	992,523

The following table summarizes, as of September 30, 2011, the carrying value of securities pledged as collateral to secure public deposits, borrowings and other purposes as permitted or required by law:



(in thousands)	Carrying Amount
To Washington and Oregon State to secure public deposits	$	237,671
To Federal Home Loan Bank to secure advances	95,139
To Federal Reserve Bank to secure borrowings	55,947
Other securities pledged	50,080
Total securities pledged as collateral	$	438,837

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 September 30, 2011 and December 31, 2010:



September 30, 2011
	Less than 12 Months					12 Months or More					Total
(in thousands)	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations	$	119,998	$	(905	)	$	275	$	(1	)	$	120,273	(906		)
State and municipal securities	11,558		(97		)	1,204		(18		)	12,762		(115		)
U.S. government and government-sponsored enterprise securities	100		—			—		—			100		—
Other securities	—		—			973		(27		)	973		(27		)
Total	$	131,656	$	(1,002	)	$	2,452	$	(46	)	$	134,108	$	(1,048	)
December 31, 2010
	Less than 12 Months					12 Months or More					Total
(in thousands)	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations	$	86,529	$	(1,025	)	$	588	$	(2	)	$	87,117	$	(1,027	)
State and municipal securities	74,755		(2,099		)	2,792		(284		)	77,547		(2,383		)
Other securities	2,275		(6		)	968		(32		)	3,243		(38		)
Total	$	163,559	$	(3,130	)	$	4,348	$	(318	)	$	167,907	$	(3,448	)

The unrealized losses on the above securities are primarily attributable to increases in market interest rates subsequent to their purchase by the Company. Management does not intend to sell any impaired securities nor does available evidence suggest it is more likely than not that management will be required to sell any impaired securities. The Company’s securities portfolio does not include any private label mortgage backed securities or investments in trust preferred securities. Management believes the nature of securities in the Company’s investment portfolio present a very high probability of collecting all contractual amounts due, as the majority of the securities held are backed by government agencies or government-sponsored enterprises. However, this recovery in value may not occur for some time, perhaps greater than the one-year time horizon or perhaps even at maturity.