Available-for-Sale Securities

Major Security Types. Available-for-sale securities as of September 30, 2013 were as follows (in thousands):



	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Debentures
U.S. government-guaranteed obligations	$	54,564	$	62	$	108	$	54,518
Government-sponsored enterprises	5,023,165		4,570		6,440		5,021,295
Other	441,137		360		1,231		440,266
Total	$	5,518,866	$	4,992	$	7,779	$	5,516,079

Available-for-sale securities as of December 31, 2012 were as follows (in thousands):



	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Debentures
U.S. government-guaranteed obligations	$	56,119	$	301	$	3	$	56,417
Government-sponsored enterprises	5,236,358		22,280		644		5,257,994
Other	457,149		867		274		457,742
Total	$	5,749,626	$	23,448	$	921	$	5,772,153

Other debentures are fully secured by U.S. government-guaranteed obligations and the payment of interest on the debentures is guaranteed by an agency of the U.S. government. The amortized cost of the Bank's available-for-sale securities includes hedging adjustments. The following table summarizes (in thousands, except number of positions) the available-for-sale securities with unrealized losses as of September 30, 2013. The unrealized losses are aggregated by major security type and length of time that individual securities have been in a continuous loss position.



	Less than 12 Months					12 Months or More					Total
	Number of Positions	Estimated Fair Value		Gross Unrealized Losses		Number of Positions	Estimated Fair Value		Gross Unrealized Losses		Number of Positions	Estimated Fair Value		Gross Unrealized Losses
Debentures
U.S. government-guaranteed obligations	3	$	35,198	$	108	—	$	—	$	—	3	$	35,198	$	108
Government-sponsored enterprises	119	2,134,921		6,440		—	—		—		119	2,134,921		6,440
Other	23	242,636		1,122		3	14,850		109		26	257,486		1,231
Total	145	$	2,412,755	$	7,670	3	$	14,850	$	109	148	$	2,427,605	$	7,779

The following table summarizes (in thousands, except number of positions) the available-for-sale securities with unrealized losses as of December 31, 2012. The unrealized losses are aggregated by major security type and length of time that individual securities have been in a continuous loss position.



	Less than 12 Months					12 Months or More					Total
	Number of Positions	Estimated Fair Value		Gross Unrealized Losses		Number of Positions	Estimated Fair Value		Gross Unrealized Losses		Number of Positions	Estimated Fair Value		Gross Unrealized Losses
Debentures
U.S. government-guaranteed obligations	1	$	11,340	$	3	—	$	—	$	—	1	$	11,340	$	3
Government-sponsored enterprises	23	448,123		629		1	2,373		15		24	450,496		644
Other	18	141,151		274		—	—		—		18	141,151		274
Total	42	$	600,614	$	906	1	$	2,373	$	15	43	$	602,987	$	921

At September 30, 2013, the gross unrealized losses on the Bank’s available-for-sale securities were $7,779,000. All of the Bank's available-for-sale securities are either guaranteed by the U.S. government, issued by government-sponsored enterprises (“GSEs”), or fully secured by collateral that is guaranteed by the U.S government. As of September 30, 2013, the U.S. government and the issuers of the Bank’s holdings of GSE debentures were rated triple-A by Moody’s Investors Service (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”) and AA+ by Standard and Poor’s (“S&P”). The Bank's holdings of other debentures were rated Aaa by Moody's and AA+ by S&P at that date; the other debentures are not rated by Fitch. Based upon the Bank's assessment of the strength of the government guaranty, the Bank expects that the U.S. government-guaranteed debentures that were in an unrealized loss position at September 30, 2013 would not be settled at an amount less than the Bank's amortized cost basis in the investments. In addition, based upon the Bank’s assessment of the creditworthiness of the issuers of the GSE debentures and the credit ratings assigned by each of the nationally recognized statistical rating organizations (“NRSROs”), the Bank expects that its holdings of GSE debentures that were in an unrealized loss position at September 30, 2013 would not be settled at an amount less than the Bank’s amortized cost bases in these investments. Further, based on the creditworthiness of the issuer of the Bank's holdings of other debentures, the U.S. government's guaranty of the payment of principal and interest on the collateral securing those debentures, and the guaranty of the payment of interest on the debentures by an agency of the U.S. government, the Bank expects that its holdings of other debentures that were in an unrealized loss position at September 30, 2013 would not be settled at an amount less than the Bank’s amortized cost bases in these investments. Because the current market value deficits associated with the Bank's available-for-sale securities are not attributable to credit quality, and because the Bank does not intend to sell the investments and it is not more likely than not that the Bank will be required to sell the investments before recovery of their amortized cost bases, the Bank does not consider any of these investments to be other-than-temporarily impaired at September 30, 2013.

Redemption Terms. The amortized cost and estimated fair value of available-for-sale securities by contractual maturity at September 30, 2013 and December 31, 2012 are presented below (in thousands).



	September 30, 2013				December 31, 2012
Maturity	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
Maturity	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
Debentures
Due in one year or less	$	5,016	$	5,019	$	—	$	—
Due after one year through five years	3,871,921		3,874,920		3,340,880		3,349,030
Due after five years through ten years	1,641,929		1,636,140		2,401,976		2,416,299
Due after ten years	—		—		6,770		6,824
Total	$	5,518,866	$	5,516,079	$	5,749,626	$	5,772,153

Interest Rate Payment Terms. The following table provides interest rate payment terms for investment securities classified as available-for-sale at September 30, 2013 and December 31, 2012 (in thousands):



	September 30, 2013		December 31, 2012
Amortized cost of available-for-sale securities
Fixed-rate	$	5,443,866	$	5,674,626
Variable-rate	75,000		75,000

Total	$	5,518,866	$	5,749,626

At September 30, 2013 and December 31, 2012, all of the Bank's fixed-rate available-for-sale securities were swapped to a variable rate.