Investment in Securities (Tables)

6 Months Ended

Jun. 30, 2015

Investment in Securities [Abstract]

Schedule of Investment Securities

	June 30, 2015
			Gross		Gross
	Amortized		Unrealized		Unrealized
(In thousands)	Cost		Gains		Losses		Fair Value
State and political subdivisions	$	335,414	$	9,858	$	1,202	$	344,070
Certificates of deposit		3,750		—		—		3,750
Total	$	339,164	$	9,858	$	1,202	$	347,820

	December 31, 2014
			Gross		Gross
	Amortized		Unrealized		Unrealized
(In thousands)	Cost		Gains		Losses		Fair Value
State and political subdivisions	$	338,469	$	14,120	$	198	$	352,391
Certificates of deposit		3,750		—		—		3,750
Total	$	342,219	$	14,120	$	198	$	356,141

Schedule of the Fair Value of Securities with Unrealized Losses

	June 30, 2015
	Less than 12 months				12 months or more				Total
	Estimated		Unrealized		Estimated		Unrealized		Estimated		Unrealized
(In thousands)	Fair Value		Losses		Fair Value		Losses		Fair Value		Losses
State and political subdivisions	$	103,552	$	1,164	$	1,195	$	38	$	104,747	$	1,202
Certificates of deposit		—		—		—		—		—		—
Total	$	103,552	$	1,164	$	1,195	$	38	$	104,747	$	1,202

	December 31, 2014
	Less than 12 months				12 months or more				Total
	Estimated		Unrealized		Estimated		Unrealized		Estimated		Unrealized
(In thousands)	Fair Value		Losses		Fair Value		Losses		Fair Value		Losses
State and political subdivisions	$	8,700	$	15	$	13,833	$	183	$	22,533	$	198
Certificates of deposit		—		—		—		—		—		—
Total	$	8,700	$	15	$	13,833	$	183	$	22,533	$	198

Schedule of Amortized Cost and Fair Value of Investment

	June 30, 2015
(In thousands)	Amortized Cost		Fair Value
Due in 1 year or less	$	23,893	$	24,055
Due after 1 year through 5 years		88,356		92,275
Due after 5 years through 10 years		130,452		134,615
Due after 10 years		96,463		96,875
Total	$	339,164	$	347,820