Investment Securities (Tables)

12 Months Ended

Dec. 31, 2017

Investments, Debt and Equity Securities [Abstract]

Schedule of marketable securities

Investment securities at December 31, 2017 and December 31, 2016 were as follows:

(In thousands)	Amortized Cost		Gross Unrealized/Unrecognized Holding Gains		Gross Unrealized/Unrecognized Holding Losses		Estimated Fair Value
2017:
Securities Available-for-Sale
Obligations of U.S. Treasury and other U.S. Government sponsored entities	$	245,000	$	—	$	2,280	$	242,720
U.S. Government sponsored entities’ asset-backed securities	852,645		4,645		8,129		849,161
Other equity securities	675		1,260		—		1,935
Total	$	1,098,320	$	5,905	$	10,409	$	1,093,816
2017:
Securities Held-to-Maturity
Obligations of states and political subdivisions	$	300,412	$	6,575	$	713	$	306,274
U.S. Government sponsored entities’ asset-backed securities	56,785		758		38		57,505
Total	$	357,197	$	7,333	$	751	$	363,779

(In thousands)	Amortized Cost		Gross Unrealized/Unrecognized Holding Gains		Gross Unrealized/Unrecognized Holding Losses		Estimated Fair Value
2016:
Securities Available-for-Sale
Obligations of U.S. Treasury and other U.S. Government sponsored entities	$	270,000	$	—	$	2,467	$	267,533
U.S. Government sponsored entities’ asset-backed securities	991,642		5,372		9,842		987,172
Other equity securities	1,119		2,315		—		3,434
Total	$	1,262,761	$	7,687	$	12,309	$	1,258,139
2016:
Securities Held-to-Maturity
Obligations of states and political subdivisions	$	188,622	$	977	$	5,148	$	184,451
U.S. Government sponsored entities’ asset-backed securities	71,211		1,097		87		72,221
Total	$	259,833	$	2,074	$	5,235	$	256,672

Schedule of unrealized loss on investments

The following table provides detail on investment securities with unrealized/unrecognized losses aggregated by investment category and length of time the individual securities had been in a continuous loss position at December 31, 2017 and December 31, 2016:

	Less than 12 Months				12 Months or Longer				Total
(In thousands)	Fair Value		Unrealized/Unrecognized Losses		Fair Value		Unrealized/Unrecognized Losses		Fair Value		Unrealized/Unrecognized Losses
2017:
Securities Available-for-Sale
Obligations of U.S. Treasury and other U.S. Government sponsored entities	$	24,931	$	70	$	217,789	$	2,210	$	242,720	$	2,280
U.S. Government sponsored entities' asset-backed securities	236,924		2,786		318,797		5,343		555,721		8,129
Total	$	261,855	$	2,856	$	536,586	$	7,553	$	798,441	$	10,409
2017:
Securities Held-to-Maturity
Obligations of states and political subdivisions	$	26,644	$	194	$	45,498	$	519	$	72,142	$	713
U.S. Government sponsored entities’ asset-backed securities	7,331		38		—		—		7,331		38
Total	$	33,975	$	232	$	45,498	$	519	$	79,473	$	751

	Less than 12 Months				12 Months or Longer				Total
(In thousands)	Fair Value		Unrealized/Unrecognized Losses		Fair Value		Unrealized/Unrecognized Losses		Fair Value		Unrealized/Unrecognized Losses
2016:
Securities Available-for-Sale
Obligations of U.S. Treasury and other U.S. Government sponsored entities	$	247,695	$	2,305	$	19,838	$	162	$	267,533	$	2,467
U.S. Government sponsored entities' asset-backed securities	612,321		9,473		27,325		369		639,646		9,842
Total	$	860,016	$	11,778	$	47,163	$	531	$	907,179	$	12,309
2016:
Securities Held-to-Maturity
Obligations of states and political subdivisions	$	134,909	$	5,148	$	—	$	—	$	134,909	$	5,148
U.S. Government sponsored entities' asset-backed securities	$	—	$	—	$	7,564	$	87	$	7,564	$	87
Total	$	134,909	$	5,148	$	7,564	$	87	$	142,473	$	5,235

Schedule of contractual maturity of debt securities

The amortized cost and estimated fair value of investments in debt securities at December 31, 2017, are shown in the following table by contractual maturity, except for asset-backed securities, which are shown as a single total, due to the unpredictability of the timing in principal repayments.

(In thousands)	Amortized Cost		Estimated Fair Value		Tax Equivalent Yield (1)
Securities Available-for-Sale
U.S. Treasury and other U.S. Government sponsored entities’ notes:
Due within one year	$	120,000	$	119,499	1.14	%
Due one through five years	125,000		123,221		1.29	%
Total	$	245,000	$	242,720	1.22	%
U.S. Government sponsored entities’ asset-backed securities	$	852,645	$	849,161	2.09	%
Securities Held-to-Maturity
Obligations of states and political subdivisions
Due five through ten years	$	2,454	$	2,462	3.61	%
Due greater than ten years	$	297,958	$	303,812	4.46	%
Total	$	300,412	$	306,274	4.46	%
U.S. Government sponsored entities’ asset-backed securities	$	56,785	$	57,505	3.16	%