| Investment Securities |
Investment Securities The following tables present the amortized cost, unrealized gains, unrealized losses and approximate fair values of debt securities as of June 30, 2022 and December 31, 2021: | | | | | | | | | | | | | | | | | | | | | | | | | June 30, 2022 | | (in thousands) | Amortized Cost | | Unrealized Gains | | Unrealized Losses | | Fair Value | | Available for sale: | | | | | | | | | U.S. Treasury and agencies | $ | 936,537 | | | $ | — | | | $ | (63,662) | | | $ | 872,875 | | | Obligations of states and political subdivisions | 314,260 | | | 672 | | | (22,824) | | | 292,108 | | Mortgage-backed securities and collateralized mortgage obligations | 2,549,277 | | | 266 | | | (297,819) | | | 2,251,724 | | | | | | | | | | | Total available for sale securities | $ | 3,800,074 | | | $ | 938 | | | $ | (384,305) | | | $ | 3,416,707 | | | Held to maturity: | | | | | | | | | | | | | | | | Mortgage-backed securities and collateralized mortgage obligations | $ | 2,637 | | | $ | 748 | | | $ | — | | | $ | 3,385 | | | | | | | | | | | Total held to maturity securities | $ | 2,637 | | | $ | 748 | | | $ | — | | | $ | 3,385 | |
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| December 31, 2021 | (in thousands) | Amortized Cost | | Unrealized Gains | | Unrealized Losses | | Fair Value | | Available for sale: | | | | | | | | | U.S. Treasury and agencies | $ | 894,969 | | | $ | 27,279 | | | $ | (4,195) | | | $ | 918,053 | | | Obligations of states and political subdivisions | 320,338 | | | 11,734 | | | (1,288) | | | 330,784 | | Mortgage-backed securities and collateralized mortgage obligations | 2,649,048 | | | 19,093 | | | (46,543) | | | 2,621,598 | | | | | | | | | | | Total available for sale securities | $ | 3,864,355 | | | $ | 58,106 | | | $ | (52,026) | | | $ | 3,870,435 | | | Held to maturity: | | | | | | | | | | | | | | | | Mortgage-backed securities and collateralized mortgage obligations | $ | 2,744 | | | $ | 770 | | | $ | — | | | $ | 3,514 | | | | | | | | | | | Total held to maturity securities | $ | 2,744 | | | $ | 770 | | | $ | — | | | $ | 3,514 | |
The Company elected to exclude accrued interest receivable from the amortized cost basis of debt securities disclosed throughout this note. Interest accrued on investment securities totaled $10.6 million and $10.4 million as of June 30, 2022 and December 31, 2021, respectively, and is included in Other Assets.
Debt securities that were in an unrealized loss position as of June 30, 2022 and December 31, 2021 are presented in the following tables, based on the length of time individual securities have been in an unrealized loss position. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| June 30, 2022 | | Less than 12 Months | | 12 Months or Longer | | Total | (in thousands) | Fair Value | | Unrealized Losses | | Fair Value | | Unrealized Losses | | Fair Value | | Unrealized Losses | | Available for sale: | | | | | | | | | | | | | U.S. Treasury and agencies | $ | 848,104 | | | $ | 58,599 | | | $ | 24,771 | | | $ | 5,063 | | | $ | 872,875 | | | $ | 63,662 | | Obligations of states and political subdivisions | 200,165 | | | 21,898 | | | 4,073 | | | 926 | | | 204,238 | | | 22,824 | | Mortgage-backed securities and collateralized mortgage obligations | 1,584,947 | | | 172,958 | | | 640,877 | | | 124,861 | | | 2,225,824 | | | 297,819 | | | Total temporarily impaired securities | $ | 2,633,216 | | | $ | 253,455 | | | $ | 669,721 | | | $ | 130,850 | | | $ | 3,302,937 | | | $ | 384,305 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
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| December 31, 2021 | | Less than 12 Months | | 12 Months or Longer | | Total | (in thousands) | Fair Value | | Unrealized Losses | | Fair Value | | Unrealized Losses | | Fair Value | | Unrealized Losses | | Available for sale: | | | | | | | | | | | | | U.S. Treasury and agencies | $ | 197,529 | | | $ | 2,749 | | | $ | 28,378 | | | $ | 1,446 | | | $ | 225,907 | | | $ | 4,195 | | Obligations of states and political subdivisions | 75,200 | | | 1,153 | | | 2,162 | | | 135 | | | 77,362 | | | 1,288 | | Mortgage-backed securities and collateralized mortgage obligations | 1,777,288 | | | 40,579 | | | 129,943 | | | 5,964 | | | 1,907,231 | | | 46,543 | | | | | | | | | | | | | | | Total temporarily impaired securities | $ | 2,050,017 | | | $ | 44,481 | | | $ | 160,483 | | | $ | 7,545 | | | $ | 2,210,500 | | | $ | 52,026 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
These unrealized losses on the debt securities held by the Company were caused by changes in market interest rates or the widening of market spreads subsequent to the initial purchase of these securities and are not due to the underlying credit of the issuers. Management monitors the published credit ratings of the issuers of the debt securities for material rating or outlook changes. Substantially all of the Company's obligations of states and political subdivisions are general obligation issuances. All of the available for sale mortgage-backed securities and collateralized mortgage obligations portfolio in an unrealized loss position at June 30, 2022 are issued or guaranteed by government sponsored enterprises. Because the decline in fair value of the debt securities is attributable to changes in interest rates or widening market spreads and not credit quality, these investments do not have an allowance for credit losses at June 30, 2022. The following table presents the contractual maturities of debt securities at June 30, 2022: | | | | | | | | | | | | | | | | | | | | | | | |
| Available For Sale | | Held To Maturity | (in thousands) | Amortized Cost | | Fair Value | | Amortized Cost | | Fair Value | | Due within one year | $ | 9,861 | | | $ | 9,865 | | | $ | — | | | $ | — | | | Due after one year through five years | 417,691 | | | 402,577 | | | 4 | | | 4 | | | Due after five years through ten years | 866,834 | | | 799,668 | | | 3 | | | 3 | | | Due after ten years | 2,505,688 | | | 2,204,597 | | | 2,630 | | | 3,378 | | | Total securities | $ | 3,800,074 | | | $ | 3,416,707 | | | $ | 2,637 | | | $ | 3,385 | |
The following table presents, as of June 30, 2022, investment securities which were pledged to secure borrowings, public deposits, and repurchase agreements as permitted or required by law: | | | | | | | | | | | | | (in thousands) | Amortized Cost | | Fair Value | | | | | | To state and local governments to secure public deposits | $ | 337,668 | | | $ | 311,000 | | | To secure repurchase agreements | 675,878 | | | 624,604 | | | Other securities pledged | 243,131 | | | 225,458 | | | Total pledged securities | $ | 1,256,677 | | | $ | 1,161,062 | |
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