2. Securities

The following tables set forth the amortized cost and estimated fair value of securities available-for-sale and held-to-maturity at the dates indicated.

	At June 30, 2013
(In Thousands)	Amortized Cost	Gross Unrealized Gains	Gross Unrealized Losses		Estimated Fair Value
Available-for-sale:
Residential mortgage-backed securities:
GSE (1) issuance REMICs and CMOs (2)	$ 222,623	$ 1,440	$ (3,605	)	$ 220,458
Non-GSE issuance REMICs and CMOs	9,175	3	(36	)	9,142
GSE pass-through certificates	18,566	937	(2	)	19,501
Total residential mortgage-backed securities	250,364	2,380	(3,643	)	249,101
Obligations of GSEs	98,673	—	(5,184	)	93,489
Fannie Mae stock	15	—	(14	)	1
Total securities available-for-sale	$ 349,052	$ 2,380	$ (8,841	)	$ 342,591
Held-to-maturity:
Residential mortgage-backed securities:
GSE issuance REMICs and CMOs	$ 1,611,169	$ 17,832	$ (16,910	)	$ 1,612,091
Non-GSE issuance REMICs and CMOs	4,648	85	—		4,733
GSE pass-through certificates	195,520	5	(7,220	)	188,305
Total residential mortgage-backed securities	1,811,337	17,922	(24,130	)	1,805,129
Obligations of GSEs	80,924	—	(4,004	)	76,920
Other	622	—	—		622
Total securities held-to-maturity	$ 1,892,883	$ 17,922	$ (28,134	)	$ 1,882,671

(1) Government-sponsored enterprise

(2) Real estate mortgage investment conduits and collateralized mortgage obligations

	At December 31, 2012
(In Thousands)	Amortized Cost	Gross Unrealized Gains	Gross Unrealized Losses		Estimated Fair Value
Available-for-sale:
Residential mortgage-backed securities:
GSE issuance REMICs and CMOs	$ 200,152	$ 5,258	$ (583	)	$ 204,827
Non-GSE issuance REMICs and CMOs	11,296	9	(86	)	11,219
GSE pass-through certificates	20,348	1,029	(2	)	21,375
Total residential mortgage-backed securities	231,796	6,296	(671	)	237,421
Obligations of GSEs	98,670	214	(5	)	98,879
Fannie Mae stock	15	—	(15	)	—
Total securities available-for-sale	$ 330,481	$ 6,510	$ (691	)	$ 336,300
Held-to-maturity:
Residential mortgage-backed securities:
GSE issuance REMICs and CMOs	$ 1,693,437	$ 27,787	$ (2,955	)	$ 1,718,269
Non-GSE issuance REMICs and CMOs	5,791	112	—		5,903
GSE pass-through certificates	257	6	(1	)	262
Total residential mortgage-backed securities	1,699,485	27,905	(2,956	)	1,724,434
Other	656	—	—		656
Total securities held-to-maturity	$ 1,700,141	$ 27,905	$ (2,956	)	$ 1,725,090

The following tables set forth the estimated fair values of securities with gross unrealized losses at the dates indicated, segregated between securities that have been in a continuous unrealized loss position for less than twelve months and those that have been in a continuous unrealized loss position for twelve months or longer at the dates indicated.

	At June 30, 2013
	Less Than Twelve Months		Twelve Months or Longer		Total
(In Thousands)	Estimated Fair Value	Gross Unrealized Losses	Estimated Fair Value	Gross Unrealized Losses	Estimated Fair Value	Gross Unrealized Losses
Available-for-sale:
GSE issuance REMICs and CMOs	$ 186,581	$ (3,605)	$ —	$ —	$ 186,581	$ (3,605	)
Non-GSE issuance REMICs and CMOs	—	—	8,712	(36)	8,712	(36	)
GSE pass-through certificates	167	(1)	45	(1)	212	(2	)
Obligations of GSEs	93,489	(5,184)	—	—	93,489	(5,184	)
Fannie Mae stock	—	—	1	(14)	1	(14	)
Total temporarily impaired securities available-for-sale	$ 280,237	$ (8,790)	$ 8,758	$ (51)	$ 288,995	$ (8,841	)
Held-to-maturity:
GSE issuance REMICs and CMOs	$ 662,993	$ (16,638)	$ 37,945	$ (272)	$ 700,938	$ (16,910	)
GSE pass-through certificates	188,174	(7,220)	—	—	188,174	(7,220	)
Obligations of GSEs	76,920	(4,004)	—	—	76,920	(4,004	)
Total temporarily impaired securities held-to-maturity	$ 928,087	$ (27,862)	$ 37,945	$ (272)	$ 966,032	$ (28,134	)

	At December 31, 2012
	Less Than Twelve Months		Twelve Months or Longer		Total
(In Thousands)	Estimated Fair Value	Gross Unrealized Losses	Estimated Fair Value	Gross Unrealized Losses	Estimated Fair Value	Gross Unrealized Losses
Available-for-sale:
GSE issuance REMICs and CMOs	$ 67,841	$ (583)	$ —	$ —	$ 67,841	$ (583	)
Non-GSE issuance REMICs and CMOs	—	—	10,709	(86)	10,709	(86	)
GSE pass-through certificates	57	(1)	47	(1)	104	(2	)
Obligations of GSEs	24,995	(5)	—	—	24,995	(5	)
Fannie Mae stock	—	—	—	(15)	—	(15	)
Total temporarily impaired securities available-for-sale	$ 92,893	$ (589)	$ 10,756	$ (102)	$ 103,649	$ (691	)
Held-to-maturity:
GSE issuance REMICs and CMOs	$ 413,651	$ (2,759)	$ 12,259	$ (196)	$ 425,910	$ (2,955	)
GSE pass-through certificates	48	(1)	—	—	48	(1	)
Total temporarily impaired securities held-to-maturity	$ 413,699	$ (2,760)	$ 12,259	$ (196)	$ 425,958	$ (2,956	)

We held 76 securities which had an unrealized loss at June 30, 2013 and 41 at December 31, 2012. At June 30, 2013 and December 31, 2012, substantially all of the securities in an unrealized loss position had a fixed interest rate and the cause of the temporary impairment was directly related to the change in interest rates. We generally view changes in fair value caused by changes in interest rates as temporary, which is consistent with our experience. None of the unrealized losses are related to credit losses. Therefore, at June 30, 2013 and December 31, 2012, the impairments were deemed temporary based on (1) the direct relationship of the decline in fair value to movements in interest rates, (2) the estimated remaining life and high credit quality of the investments and (3) the fact that we had no intention to sell these securities and it was not more likely than not that we would be required to sell these securities before their anticipated recovery of the remaining amortized cost basis and we expected to recover the entire amortized cost basis of the security.

During the six months ended June 30, 2013, proceeds from sales of securities from the available-for-sale portfolio totaled $41.6 million, resulting in gross realized gains totaling $2.1 million. During the six months ended June 30, 2012, proceeds from sales of securities from the available-for-sale portfolio totaled $54.3 million, resulting in gross realized gains totaling $2.5 million.

At June 30, 2013, available-for-sale debt securities excluding mortgage-backed securities had an amortized cost of $98.7 million, a fair value of $93.5 million and contractual maturities in 2021 and 2022. At June 30, 2013, held-to-maturity debt securities excluding mortgage-backed securities had an amortized cost of $81.5 million, a fair value of $77.5 million and contractual maturities in 2020 and 2023. Actual maturities may differ from contractual maturities because issuers may have the right to prepay or call obligations with or without prepayment penalties.

The balance of accrued interest receivable for securities totaled $6.2 million at June 30, 2013 and $5.7 million at December 31, 2012.

At June 30, 2013, we held securities with an amortized cost of $179.6 million which are callable within one year and at various times thereafter.