Investment Securities

The amortized cost and fair value of investment securities are shown in the following tables. Management performs a quarterly evaluation of investment securities for any other-than-temporary impairment. For the three-month and nine-month periods ended September 30, 2015 and 2014, there were no investment securities deemed to be other-than-temporarily impaired.

Investment securities at September 30, 2015, were as follows:



Securities Available-for-Sale (In thousands)	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses		Estimated Fair Value
Obligations of U.S. Treasury and other U.S. Government sponsored entities	$	546,888	$	260	$	2,097	$	545,051
U.S. Government sponsored entities' asset-backed securities	734,014		13,766		2,000		745,780
Other equity securities	1,120		1,513		—		2,633
Total	$	1,282,022	$	15,539	$	4,097	$	1,293,464



Securities Held-to-Maturity (In thousands)	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses		Estimated Fair Value
U.S. Government sponsored entities' asset-backed securities	$	111,415	$	2,110	$	82	$	113,443
Obligations of states and political subdivisions	$	6,094	$	48	$	—	$	6,142
Total	$	117,509	$	2,158	$	82	$	119,585

Securities with unrealized losses at September 30, 2015, were as follows:



	Unrealized loss position for less than 12 months				Unrealized loss position for 12 months or longer				Total
(In thousands)	Fair value		Unrealized losses		Fair value		Unrealized losses		Fair value		Unrealized losses
Securities Available-for-Sale
Obligations of U.S. Treasury and other U.S. Government sponsored entities	$	179,452	$	548	$	215,339	$	1,549	$	394,791	$	2,097
U.S. Government sponsored entities' asset-backed securities	$	—	$	—	$	121,059	$	2,000	$	121,059	$	2,000
Total	$	179,452	$	548	$	336,398	$	3,549	$	515,850	$	4,097
Securities Held-to-Maturity
U.S. Government sponsored entities' asset-backed securities	$	—	$	—	$	7,899	$	82	$	7,899	$	82

Investment securities at December 31, 2014, were as follows:



Securities Available-for-Sale (In thousands)	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses		Estimated Fair Value
Obligations of U.S. Treasury and other U.S. Government sponsored entities	$	546,886	$	11	$	8,833	$	538,064
U.S. Government sponsored entities' asset-backed securities	751,974		13,421		4,242		761,153
Other equity securities	1,120		1,578		—		2,698
Total	$	1,299,980	$	15,010	$	13,075	$	1,301,915



Securities Held-to-Maturity (In thousands)	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses		Estimated Fair Value
U.S. Government sponsored entities' asset-backed securities	$	140,562	$	3,088	$	160	$	143,490

Securities with unrealized losses at December 31, 2014, were as follows:



	Unrealized loss position for less than 12 months				Unrealized loss position for 12 months or longer				Total
(In thousands)	Fair value		Unrealized losses		Fair value		Unrealized losses		Fair value		Unrealized losses
Securities Available-for-Sale
Obligations of U.S. Treasury and other U.S. Government sponsored entities	$	119,913	$	87	$	388,140	$	8,746	$	508,053	$	8,833
U.S. Government sponsored entities' asset-backed securities	73,276		136		170,430		4,106		243,706		4,242
Total	$	193,189	$	223	$	558,570	$	12,852	$	751,759	$	13,075
Securities Held-to-Maturity
U.S. Government sponsored entities' asset-backed securities	$	8,032	$	148	$	2,714	$	12	$	10,746	$	160

Management does not believe any of the unrealized losses at September 30, 2015 or December 31, 2014 represented other-than-temporary impairment. Should the impairment of any of these securities become other-than-temporary, the cost basis of the investment will be reduced and the resulting loss recognized within net income in the period the other-than-temporary impairment is identified.

Park’s U.S. Government sponsored entities' asset-backed securities consist of 15-year residential mortgage-backed securities and collateralized mortgage obligations.

The amortized cost and estimated fair value of investments in debt securities at September 30, 2015, are shown in the following table by contractual maturity or the expected call date, except for asset-backed securities, which are shown as a single total, due to the unpredictability of the timing of principal repayments.



Securities Available-for-Sale (In thousands)	Amortized cost		Fair value		Tax equivalent yield
U.S. Treasury and sponsored entities' obligations:
Due within one year	150,000		150,257		1.39	%
Due five through ten years	396,888		394,794		2.43	%
Total	$	546,888	$	545,051	2.14	%


U.S. Government sponsored entities' asset-backed securities:	$	734,014	$	745,780	2.31	%



Securities Held-to-Maturity (In thousands)	Amortized cost		Fair value		Tax equivalent yield
Obligations of state and political subdivisions:
Due five through ten years	$	6,094	$	6,142	5.03	%
Total	$	6,094	$	6,142	5.03	%

U.S. Government sponsored entities' asset-backed securities	$	111,415	$	113,443	3.49	%

The $545.1 million of Park’s securities shown at fair value in the above table as U.S. Treasury and sponsored entities' obligations are callable notes. These callable securities have final maturities of 2 to 7 years. Of the $545.1 million reported at September 30, 2015, $150.3 million were expected to be called. The remaining average life of the investment portfolio is estimated to be 5.2 years.

There were no sales of investment securities during the three-month and nine-month periods ended September 30, 2015 and the three-month period ended September 30, 2014. Securities with an amortized cost of $468,000 were sold at a gain of $20,000 during the nine-month period ended September 30, 2014.