XML 40 R29.htm IDEA: XBRL DOCUMENT v3.20.2
Securities (Tables)
 9 Months Ended
Sep. 30, 2020
Investments, Debt and Equity Securities [Abstract]  
Debt Securities, Held-to-maturity [Table Text Block] A summary of the amortized cost, fair value and allowance for credit losses related to securities held to maturity as of September 30, 2020 and December 31, 2019 is presented below.
Amortized
Cost		Gross
Unrealized
Gains		Gross
Unrealized
Losses		Estimated
Fair Value		Allowance
for Credit
Losses		Net
Carrying
Amount
September 30, 2020
Residential mortgage-backed securities
$529,290 $45,504 $— $574,794 $— $529,290 
States and political subdivisions
1,420,754 61,808 — 1,482,562 (160)1,420,594 
Other1,500 — 1 1,499 — 1,500 
Total$1,951,544 $107,312 $1 $2,058,855 $(160)$1,951,384 
December 31, 2019
Residential mortgage-backed securities
$530,861 $22 $9,365 $521,518 $— $530,861 
States and political subdivisions
1,497,644 28,909 896 1,525,657 — 1,497,644 
Other1,500 — — 1,500 — 1,500 
Total$2,030,005 $28,931 $10,261 $2,048,675 $— $2,030,005 
Moody's and Standard & Poor's Bond Ratings [Table Text Block]
The following table summarizes Moody's and/or Standard & Poor's bond ratings for our portfolio of held-to-maturity securities issued by States and political subdivisions and other securities as of September 30, 2020:
States and Political Subdivisions
Not Guaranteed or Pre-RefundedGuaranteed by the Texas PSFPre-RefundedTotalOther
Securities
Aaa/AAA$115,385 $797,659 $332,240 $1,245,284 $— 
Aa/AA
112,614 — — 112,614 — 
A
62,856 — — 62,856 — 
Not rated— — — — 1,500 
Total$290,855 $797,659 $332,240 $1,420,754 $1,500 
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Table Text Block]
The following table details activity in the allowance for credit losses on held-to-maturity securities during the three and nine months ended September 30, 2020.
Three Months Ended
September 30, 2020		Nine Months Ended September 30, 2020
Beginning balance$172 $— 
Impact of adopting ASC 326— 215 
Credit loss expense (benefit)(12)(55)
Ending balance$160 $160 
Amortized Cost, Estimated Fair Value and Allowance for Credit Losses of Securities Available for Sale A summary of the amortized cost, fair value and allowance for credit losses related to securities available for sale as of September 30, 2020 and December 31, 2019 is presented below.
Amortized
Cost		Gross
Unrealized
Gains		Gross
Unrealized
Losses		Allowance
for Credit
Losses		Estimated
Fair Value
September 30, 2020
U.S. Treasury$1,084,210 $40,755 $— $— $1,124,965 
Residential mortgage-backed securities
2,092,184 72,021 43 — 2,164,162 
States and political subdivisions
6,695,946 577,059 — — 7,273,005 
Other42,348 — — — 42,348 
Total$9,914,688 $689,835 $43 $— $10,604,480 
December 31, 2019
U.S. Treasury$1,941,283 $18,934 $12,084 $— $1,948,133 
Residential mortgage-backed securities
2,176,275 32,608 1,289 — 2,207,594 
States and political subdivisions
6,717,344 353,857 204 — 7,070,997 
Other42,867 — — — 42,867 
Total$10,877,769 $405,399 $13,577 $— $11,269,591 
Securities, with Unrealized Losses Segregated by Length of Impairment
The table below summarizes, as of September 30, 2020, securities available for sale in an unrealized loss position for which an allowance for credit losses has not been recorded, aggregated by type of security and length of time in a continuous unrealized loss position.
Less than 12 MonthsMore than 12 MonthsTotal
Estimated
Fair Value		Unrealized
Losses		Estimated
Fair Value		Unrealized
Losses		Estimated
Fair Value		Unrealized
Losses
Residential mortgage-backed securities
$7,527 $42 $124 $1 $7,651 $43 
Total$7,527 $42 $124 $1 $7,651 $43 
Amortized Cost and Estimated Fair Value of Securities, Excluding Trading Securities, Presented by Contractual Maturity The following table summarizes the maturity distribution schedule of securities held to maturity and securities available for sale as of September 30, 2020. Mortgage-backed securities are included in maturity categories based on their stated maturity date. Expected maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations. Other securities classified as available for sale include stock in the Federal Reserve Bank and the Federal Home Loan Bank, which have no maturity date. These securities have been included in the total column only.
Within 1 Year1 - 5 Years5 - 10 YearsAfter 10 YearsTotal
Held To Maturity
Amortized Cost
Residential mortgage-backed securities$— $231 $516,368 $12,691 $529,290 
States and political subdivisions55,180 355,409 399,377 610,788 1,420,754 
Other— 1,500 — — 1,500 
Total$55,180 $357,140 $915,745 $623,479 $1,951,544 
Estimated Fair Value
Residential mortgage-backed securities$— $233 $560,456 $14,105 $574,794 
States and political subdivisions56,043 369,536 411,517 645,466 1,482,562 
Other— 1,499 — — 1,499 
Total$56,043 $371,268 $971,973 $659,571 $2,058,855 
Available For Sale
Amortized Cost
U. S. Treasury$299,355 $784,855 $— $— $1,084,210 
Residential mortgage-backed securities175 45,832 22,949 2,023,228 2,092,184 
States and political subdivisions201,529 1,029,750 696,654 4,768,013 6,695,946 
Other— — — — 42,348 
Total$501,059 $1,860,437 $719,603 $6,791,241 $9,914,688 
Estimated Fair Value
U. S. Treasury$305,121 $819,844 $— $— $1,124,965 
Residential mortgage-backed securities182 47,995 23,439 2,092,546 2,164,162 
States and political subdivisions204,107 1,127,267 757,126 5,184,505 7,273,005 
Other— — — — 42,348 
Total$509,410 $1,995,106 $780,565 $7,277,051 $10,604,480 
Sales of Securities Available for Sale Sales of securities available for sale were as follows:
Three Months Ended
September 30,		Nine Months Ended
September 30,
2020201920202019
Proceeds from sales$— $4,944,537 $1,162,352 $8,236,066 
Gross realized gains— 96 108,989 899 
Gross realized losses— — — (634)
Tax (expense) benefit of securities gains/losses— (21)(22,888)(56)
Premium Amortization and Discount Accretion Included in Income on Securities [Table Text Block] Premium amortization and discount accretion included in interest income on securities was as follows:
Three Months Ended
September 30,		Nine Months Ended
September 30,
2020201920202019
Premium amortization$(31,540)$(29,511)$(94,873)$(88,798)
Discount accretion637 1,274 1,793 3,835 
Net (premium amortization) discount accretion$(30,903)$(28,237)$(93,080)$(84,963)
Trading Account Securities, at Estimated Fair Value Trading account securities, at estimated fair value, were as follows:
September 30,
2020		December 31,
2019
U.S. Treasury$24,495 $24,298 
States and political subdivisions1,313 — 
Total$25,808 $24,298 
Net Gains and Losses on Trading Account Securities
Net gains and losses on trading account securities were as follows:
Three Months Ended
September 30,		Nine Months Ended
September 30,
2020201920202019
Net gain on sales transactions$159 $731 $933 $1,789 
Net mark-to-market gains (losses)1 (201)94 (170)
Net gain (loss) on trading account securities$160 $530 $1,027 $1,619