Investment Securities (Tables)

3 Months Ended

Mar. 31, 2015

Investments, Debt and Equity Securities [Abstract]

Amortized Cost and Estimated Fair Values of Investments in Debt and Equity Securities

The amortized cost and estimated fair values of investments in debt and equity securities are summarized in the following tables:

	March 31, 2015
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
Securities Available for Sale
Obligations of U.S. government corporations and agencies	$	206,476	$	4,221	$	(162	)	$	210,535
Obligations of states and political subdivisions		9,700		36		(80	)		9,656
Corporate debt securities		1,895		10		—			1,905
Marketable equity securities		3,000		30		—			3,030
Total securities available for sale	$	221,071	$	4,297	$	(242	)	$	225,126
Securities Held to Maturity
Obligations of U.S. government corporations and agencies	$	786,889	$	15,726	$	(339	)	$	802,276
Obligations of states and political subdivisions		15,593		95		(171	)		15,517
Total securities held to maturity	$	802,482	$	15,821	$	(510	)	$	817,793
	December 31, 2014
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
Securities Available for Sale
Obligations of U.S. government corporations and agencies	$	71,144	$	4,001	$	(25	)	$	75,120
Obligations of states and political subdivisions		3,130		45		—			3,175
Corporate debt securities		1,891		17		—			1,908
Marketable equity securities		3,000		2		—			3,002
Total securities available for sale	$	79,165	$	4,065	$	(25	)	$	83,205
Securities Held to Maturity
Obligations of U.S. government corporations and agencies	$	660,836	$	13,055	$	(677	)	$	673,214
Obligations of states and political subdivisions		15,590		130		(155	)		15,565
Total securities held to maturity	$	676,426	$	13,185	$	(832	)	$	688,779

Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity

For purposes of the following table, the entire outstanding balance of these mortgage-backed securities issued by U.S. government corporations and agencies is categorized based on final maturity date.

Investment Securities	Available for Sale				Held to Maturity
(In thousands)	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
Due in one year	$	1,896	$	1,906		—		—
Due after one year through five years		4,014		4,202		—		—
Due after five years through ten years		31,848		33,332	$	1,125	$	1,134
Due after ten years		183,313		185,686		801,357		816,659
Totals	$	221,071	$	225,126	$	802,482	$	817,793

Gross Unrealized Losses on Investment

Gross unrealized losses on investment securities and the fair value of the related securities, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, were as follows:

	Less than 12 months					12 months or more					Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss			Fair Value		Unrealized Loss
	(in thousands)
March 31, 2015
Securities Available for Sale:
Obligations of U.S. government corporations and agencies	$	78,146	$	(162	)		—		—		$	78,146	$	(162	)
Obligations of states and political subdivisions		6,422		(80	)		—		—			6,422		(80	)
Corporate debt securities		—		—			—		—			—		—
Marketable equity securities		—		—			—		—			—		—
Total securities available-for-sale	$	84,568	$	(242	)		—		—		$	84,568	$	(242	)
Securities Held to Maturity:
Obligations of U.S. government corporations and agencies	$	162,549	$	(339	)		—		—		$	162,549	$	(339	)
Obligations of states and political subdivisions		2,419		(27	)	$	1,075	$	(144	)		3,494		(171	)
Corporate debt securities		—		—			—		—			—		—
Total securities held-to-maturity	$	164,968	$	(366	)	$	1,075	$	(144	)	$	166,043	$	(510	)
	Less than 12 months					12 months or more					Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss			Fair Value		Unrealized Loss
	(in thousands)
December 31, 2014
Securities Available for Sale:
Obligations of U.S. government corporations and agencies	$	6,774	$	(25	)		—		—		$	6,774	$	(25	)
Obligations of states and political subdivisions		—		—			—		—			—		—
Corporate debt securities		—		—			—		—			—		—
Marketable equity securities		—		—			—		—			—		—
Total securities available-for-sale	$	6,774	$	(25	)		—		—		$	6,774	$	(25	)
Securities Held to Maturity:
Obligations of U.S. government corporations and agencies	$	335	$	(1	)	$	56,288	$	(676	)	$	56,623	$	(677	)
Obligations of states and political subdivisions		1,600		(26	)		1,858		(129	)		3,458		(155	)
Corporate debt securities		—		—			—		—			—		—
Total securities held-to-maturity	$	1,935	$	(27	)	$	58,146	$	(805	)	$	60,081	$	(832	)