The amortized cost and estimated fair values of investment securities at March 31, 2013 and December 31, 2012 consisted of the following (dollars in thousands):

	March 31, 2013
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Debt securities:
Mortgage-backed securities	$	205,981	$	5,253	$	(427	)	$	210,807
Obligations of states and political subdivisions		27,620		1,761		—			29,381
Corporate bonds		1,506		100		—			1,606
Equity securities:
Corporate stock		64		23		—			87
	$	235,171	$	7,137	$	(427	)	$	241,881

	December 31, 2012
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Debt securities:
Mortgage-backed securities	$	195,444	$	5,661	$	(590	)	$	200,515
Obligations of states and political subdivisions		27,682		1,974		—			29,656
Corporate bonds		1,507		87		—			1,594
Equity securities:
Corporate stock		64		10		—			74
	$	224,697	$	7,732	$	(590	)	$	231,839

Net unrealized gains on available-for-sale investment securities totaling $4,026,000 were recorded, net of $2,684,000 in tax liabilities, as accumulated other comprehensive income within shareholders’ equity at March 31, 2013. There were not any proceeds nor gross realized gains from the sale and call of available-for-sale investment securities for the three-month period ended March 31, 2013. There were no transfers of available-for-sale investment securities for the three-month period ended March 31, 2013.

Net unrealized gains on available-for-sale investment securities totaling $4,285,000 were recorded, net of $2,857,000 in tax liabilities, as accumulated other comprehensive income within shareholders’ equity at December 31, 2012. Proceeds and gross realized gains from the sale and call of available-for-sale investment securities for the three-month period ended March 31, 2012 totaled $4,908,000 and $64,000, respectively. There were no transfers of available-for-sale investment securities for the three-month period ended March 31, 2012.

Gross

Estimated

Amortized

Unrealized

Fair

Cost

Gains

Losses

Value

Debt securities:

Mortgage-backed securities

1,900

128

—

2,028

December 31, 2012

Gross

Estimated

Amortized

Unrealized

Fair

Cost

Gains

Losses

Value

Debt securities:

Mortgage-backed securities

2,117

138

—

2,255

There were no sales or transfers of held-to-maturity investment securities for the periods ended March 31, 2013 and March 31, 2012. Investment securities with unrealized losses at March 31, 2013 and December 31, 2012 are summarized and classified according to the duration of the loss period as follows (dollars in thousands):

March 31, 2013	Less than 12 Months					12 Months or More				Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Available-for-Sale

Debt securities:
Mortgage-backed securities	$	38,658	$	(427	)		—		—	$	38,658	$	(427	)
	$	38,658	$	(427	)	$	—	$	—	$	38,658	$	(427	)

December 31, 2012	Less than 12 Months					12 Months or More				Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Available-for-Sale

Debt securities:
Mortgage-backed securities	$	37,440	$	(590	)		—		—	$	37,440	$	(590	)
	$	37,440	$	(590	)	$	—	$	—	$	37,440	$	(590	)

There were no held-to-maturity investment securities with unrealized losses as of March 31, 2013 or December 31, 2012.

At March 31, 2013, the Company held 206 securities of which 16 were in a loss position for less than twelve months and none were in a loss position for twelve months or more. Of the 16 securities in a loss position, all are mortgage-backed securities. At December 31, 2012, the Company held 196 securities of which 16 were in a loss position for less than twelve months and none were in a loss position for twelve months or more. All 16 securities in a loss position were mortgage-backed securities.

The unrealized loss on the Company’s investments in mortgage-backed securities is primarily driven by interest rates. Because the decline in market value is attributable to a change in interest rates and not credit quality, and because the Company has the ability and intent to hold these investments until recovery of fair value, which may be until maturity, management does not consider these investments to be other-than-temporarily impaired.

The amortized cost and estimated fair values of investment securities at March 31, 2013 by contractual maturity are shown below (dollars in thousands).

	Available-for-Sale				Held-to-Maturity
	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value

Within one year	$	1,010	$	1,016
After one year through five years		3,382		3,567
After five years through ten years		11,644		12,456
After ten years		13,090		13,948
		29,126		30,987
Investment securities not due at a single maturity date:
Mortgage-backed securities		205,981		210,807	$	1,900	$	2,028
Corporate stock		64		87		—		—
	$	235,171	$	241,881	$	1,900	$	2,028

Expected maturities will differ from contractual maturities because the issuers of the securities may have the right to call or prepay obligations with or without call or prepayment penalties.