The amortized cost, gross unrealized gains and losses and estimated fair values of available for sale ("AFS") and held to maturity ("HTM") debt securities are presented below.


(Dollars in Thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized (Losses)		Fair Value
At December 31, 2020
Debt securities AFS
SBA securities	$	156,929	$	5,255	$	(175)	$	162,009
Obligations of states and political subdivisions	2,823		17		—		2,840
Non-bank qualified obligations of states and political subdivisions	299,830		9,808		—		309,638
Asset-backed securities	323,589		2,752		(3,465)		322,876
Mortgage-backed securities	418,390		12,685		(314)		430,761
Total debt securities AFS	$	1,201,561	$	30,517	$	(3,954)	$	1,228,124


(Dollars in Thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized (Losses)		Fair Value
At September 30, 2020
Debt securities AFS
SBA securities	$	159,722	$	5,391	$	(158)	$	164,955
Obligations of states and political subdivisions	825		16		—		841
Non-bank qualified obligations of states and political subdivisions	314,819		8,978		(23)		323,774
Asset-backed securities	329,139		2,015		(6,229)		324,925
Mortgage-backed securities	439,879		14,567		(839)		453,607
Total debt securities AFS	$	1,244,384	$	30,967	$	(7,249)	$	1,268,102


(Dollars in Thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized (Losses)		Fair Value
At December 31, 2020
Debt securities HTM
Non-bank qualified obligations of states and political subdivisions	$	76,176	$	1,414	$	—	$	77,590
Mortgage-backed securities	5,152		185		—		5,337
Total debt securities HTM	$	81,328	$	1,599	$	—	$	82,927


(Dollars in Thousands)	Amortized Cost		Gross Unrealized Gain		Gross Unrealized (Losses)		Fair Value
At September 30, 2020
Debt securities HTM
Non-bank qualified obligations of states and political subdivisions	$	87,183	$	1,040	$	(29)	$	88,194
Mortgage-backed securities	5,427		124		—		5,551
Total debt securities HTM	$	92,610	$	1,164	$	(29)	$	93,745

Gross unrealized losses and fair value, aggregated by investment category and length of time that individual securities have been in a continuous loss position, were as follows:


	LESS THAN 12 MONTHS				OVER 12 MONTHS				TOTAL
(Dollars in Thousands)	Fair Value		Unrealized (Losses)		Fair Value		Unrealized (Losses)		Fair Value		Unrealized (Losses)
At December 31, 2020
Debt securities AFS
SBA securities	$	40,938	$	(81)	$	18,623	$	(94)	$	59,561	$	(175)


Asset-backed securities	60,713		(136)		200,240		(3,329)		260,953		(3,465)
Mortgage-backed securities	62,494		(314)		—		—		62,494		(314)
Total debt securities AFS	$	164,145	$	(531)	$	218,863	$	(3,423)	$	383,008	$	(3,954)


	LESS THAN 12 MONTHS				OVER 12 MONTHS				TOTAL
(Dollars in Thousands)	Fair Value		Unrealized (Losses)		Fair Value		Unrealized (Losses)		Fair Value		Unrealized (Losses)
At September 30, 2020
Debt securities AFS
SBA securities	$	32,257	$	(102)	$	9,875	$	(56)	$	42,132	$	(158)

Non-bank qualified obligations of states and political subdivisions	6,265		(6)		3,103		(17)		9,368		(23)
Asset-backed securities	106,474		(1,089)		178,686		(5,140)		285,160		(6,229)
Mortgage-backed securities	138,338		(839)		—		—		138,338		(839)
Total debt securities AFS	$	283,334	$	(2,036)	$	191,664	$	(5,213)	$	474,998	$	(7,249)


	LESS THAN 12 MONTHS				OVER 12 MONTHS				TOTAL
(Dollars in Thousands)	Fair Value		Unrealized (Losses)		Fair Value		Unrealized (Losses)		Fair Value		Unrealized (Losses)
At September 30, 2020
Debt securities HTM
Non-bank qualified obligations of states and political subdivisions	7,397		(9)		3,637		(20)		11,034		(29)

Total debt securities HTM	$	7,397	$	(9)	$	3,637	$	(20)	$	11,034	$	(29)

The adoption of CECL was inconsequential to debt securities AFS. At December 31, 2020, there was no ACL for debt securities AFS. At December 31, 2020, there were 27 securities AFS in an unrealized loss position. Management assessed each investment security with unrealized losses for credit impairment and determined substantially all unrealized losses on these securities were due to credit spreads and interest rates versus credit impairment. As part of that assessment, management evaluated and concluded that it is more-likely-than-not that the Company will not be required and does not intend to sell any of the securities prior to recovery of the amortized cost.

The amortized cost and fair value of debt securities by contractual maturity are shown below. Certain securities have call features that allow the issuer to call the security prior to maturity. Expected maturities may differ from contractual maturities in mortgage-backed securities ("MBS") because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. Therefore, MBS are not included in the maturity categories in the following maturity summary. The expected maturities of certain SBA securities may differ from contractual maturities because the borrowers may have the right to prepay the obligation. However, certain prepayment penalties may apply.


Securities AFS at Fair Value	Amortized Cost		Fair Value
(Dollars in Thousands)
At December 31, 2020
Due in one year or less	$	720	$	724
Due after one year through five years	22,799		23,707
Due after five years through ten years	32,099		33,738
Due after ten years	727,553		739,194
	783,171		797,363
Mortgage-backed securities	418,390		430,761
Total securities AFS, at fair value	$	1,201,561	$	1,228,124


(Dollars in Thousands)	Amortized Cost		Fair Value
At September 30, 2020
Due in one year or less	$	1,385	$	1,398
Due after one year through five years	20,805		21,769
Due after five years through ten years	32,441		34,025
Due after ten years	749,874		757,303
	804,505		814,495
Mortgage-backed securities	439,879		453,607
Total securities AFS, at fair value	$	1,244,384	$	1,268,102


Securities HTM at Fair Value	Amortized Cost		Fair Value
(Dollars in Thousands)
At December 31, 2020



Due after ten years	$	76,176	$	77,590
	76,176		77,590
Mortgage-backed securities	5,152		5,337
Total securities HTM, at cost	$	81,328	$	82,927


(Dollars in Thousands)	Amortized Cost		Fair Value
At September 30, 2020



Due after ten years	$	87,183	$	88,194
	87,183		88,194
Mortgage-backed securities	5,427		5,551
Total securities HTM, at cost	$	92,610	$	93,745

Other investments, at cost, include equity securities without a readily determinable fair value, which are included in other assets on the Condensed Consolidated Statements of Financial Condition, and shares of stock in the Federal Reserve Bank (the "FRB") of Minneapolis and the FHLB of Des Moines.

Equity securities without a readily determinable fair value totaled $13.7 million at December 31, 2020 and $11.0 million at September 30, 2020.

The Bank is required by federal law to subscribe to capital stock (divided into shares of $100 each) as a member of the FRB of Minneapolis with an amount equal to six per centum of the paid-up capital stock and surplus. One-half of the subscription is paid at time of application, and one-half is subject to call of the Board of Governors of the Federal Reserve System. FRB of Minneapolis stock held by the Bank totaled $19.7 million at December 31, 2020 and September 30, 2020. These equity securities are 'restricted' in that they can only be owned by member banks.

The Company's borrowings from the FHLB are secured by a blanket collateral agreement with respect to a percentage of unencumbered loans and the pledge of specific investment securities. Such advances can be made pursuant to several different credit programs, each of which has its own interest rate and range of maturities.

The investments in the FHLB stock are required investments related to the Company's membership in and current borrowings from the FHLB of Des Moines. The investments in the FHLB of Des Moines could be adversely impacted by the financial operations of the FHLB and actions of their regulator, the Federal Housing Finance Agency.

The FHLB stock is carried at cost since it is generally redeemable at par value. The carrying value of the stock held at the FHLB was $7.5 million at December 31, 2020 and September 30, 2020. The absence of change in FHLB stock directly correlates with no short-term borrowings balances at both December 31, 2020 and September 30, 2020.

These equity securities are ‘restricted’ in that they can only be sold back to the respective institution from which they were acquired or another member institution at par. Therefore, FRB and FHLB stocks are less liquid than other marketable equity securities, and the fair value approximates cost. The Company evaluates impairment for investments held at cost on at least an annual basis based on the ultimate recoverability of the par value. There was a $0.9 million impairment recognized for such investments for the three months ended December 31, 2020.