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Securities (Tables)

12 Months Ended

Dec. 31, 2020

Marketable Securities [Abstract]

Trading Securities [Table Text Block]

The fair value and net unrealized gain (loss) included in trading securities is as follows (in thousands):

						December 31, 2020												December 31, 2019
						Fair Value						Net Unrealized Gain (Loss)						Fair Value						Net Unrealized Gain (Loss)
U.S. government securities						$	9,183					$	—					$	44,264					$	6
Residential agency mortgage-backed securities						4,669,148						(3,624)						1,504,651						2,293
Municipal securities						19,172						42						26,196						60
Asset-backed securities						—						—						14,084						(21)
Other debt securities						10,472						22						34,726						21
Total trading securities						$	4,707,975					$	(3,560)					$	1,623,921					$	2,359

Investment Securities (Held-to-Maturity) [Table Text Block]

The amortized cost and fair values of investment securities are as follows (in thousands):

						December 31, 2020
						Amortized						Fair						Gross Unrealized
						Cost						Value						Gain						Loss
Municipal securities						$	229,245					$	255,270					$	26,169					$	(144)
Residential agency mortgage-backed securities						8,913						9,790						877						—
Other debt securities						7,373						7,371						—						(2)
Total investment securities						$	245,531					$	272,431					$	27,046					$	(146)
Allowance for credit losses1						(688)
Investment securities, net of allowance						$	244,843					$	272,431					$	27,046					$	(146)

1 Effective with the adoption of FASB ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326) on January 1, 2020.

						December 31, 2019
						Amortized						Fair						Gross Unrealized
						Cost						Value						Gain						Loss
Municipal securities						$	274,535					$	295,032					$	20,797					$	(300)
Residential agency mortgage-backed securities						10,676						11,164						488						—
Other debt securities						8,207						8,206						—						(1)
Total investment securities						$	293,418					$	314,402					$	21,285					$	(301)

The amortized cost and fair values of investment securities at December 31, 2020, by contractual maturity, are as shown in the following table (dollars in thousands):

						Less than One Year						One to Five Years						Six to Ten Years						Over Ten Years						Total						Weighted Average Maturity1
Fixed maturity debt securities:
Amortized cost						$	31,029					$	76,646					$	119,966					$	8,977					$	236,618					4.90
Fair value						31,459						83,944						138,101						9,137						262,641
Residential mortgage-backed securities:
Amortized cost																														$	8,913					2
Fair value																														9,790
Total investment securities:
Amortized cost																														$	245,531
Fair value																														272,431

1Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without penalty.

2The average expected lives of residential mortgage-backed securities were 4.0 years based upon current prepayment assumptions.

Temporarily Impaired Investment Securities

(in thousands):

						December 31, 2020
						Number of Securities						Less Than 12 Months												12 Months or Longer												Total
												Fair Value						Unrealized Loss						Fair Value						Unrealized Loss						Fair Value						Unrealized Loss
Investment:
Municipal securities						6						$	2,451					$	40					$	2,043					$	104					$	4,494					$	144
Other debt securities						2						$	250					$	1					$	25					$	1					$	275					$	2
Total investment securities						8						$	2,701					$	41					$	2,068					$	105					$	4,769					$	146

						December 31, 2019
						Number of Securities						Less Than 12 Months												12 Months or Longer												Total
												Fair Value						Unrealized Loss						Fair Value						Unrealized Loss						Fair Value						Unrealized Loss
Investment:
Municipal securities						15						$	1,001					$	1					$	9,747					$	299					$	10,748					$	300
Other debt securities						2						275						1						—						—						275						1
Total investment securities						17						$	1,276					$	2					$	9,747					$	299					$	11,023					$	301

Available for Sale Securities [Table Text Block]

The amortized cost and fair value of available for sale securities are as follows (in thousands):

						December 31, 2020
						Amortized						Fair						Gross Unrealized
						Cost						Value						Gain						Loss
U.S. Treasury						$	500					$	508					$	8					$	—
Municipal securities						165,318						167,979						2,666						(5)
Mortgage-backed securities:
Residential agency						9,019,013						9,340,471						328,183						(6,725)
Residential non-agency						17,563						32,770						15,207						—
Commercial agency						3,406,956						3,508,465						103,590						(2,081)
Other debt securities						500						472						—						(28)
Total available for sale securities						$	12,609,850					$	13,050,665					$	449,654					$	(8,839)

						December 31, 2019
						Amortized						Fair						Gross Unrealized
						Cost						Value						Gain						Loss
U.S. Treasury						$	1,598					$	1,600					$	2					$	—
Municipal securities						1,789						1,861						72						—
Mortgage-backed securities:
Residential agency						7,956,297						8,046,096						104,912						(15,113)
Residential non-agency						25,968						41,609						15,641						—
Commercial agency						3,145,342						3,178,005						37,808						(5,145)
Other debt securities						500						472						—						(28)
Total available for sale securities						$	11,131,494					$	11,269,643					$	158,435					$	(20,286)

The amortized cost and fair values of available for sale securities at December 31, 2020, by contractual maturity, are as shown in the following table (dollars in thousands):

			Less than One Year						One to Five Years						Six to Ten Years						Over Ten Years						Total						Weighted Average Maturity1
Fixed maturity debt securities:
Amortized cost			$	78,673					$	1,413,405					$	1,472,918					$	608,278					$	3,573,274					7.79
Fair value			78,918						1,469,630						1,498,376						630,500						3,677,424
Residential mortgage-backed securities:
Amortized cost																											$	9,036,576					2
Fair value																											9,373,241
Total available-for-sale securities:
Amortized cost																											$	12,609,850
Fair value																											13,050,665

1Expected maturities may differ from contractual maturities, because borrowers may have the right to call or prepay obligations with or without penalty.

2The average expected lives of residential mortgage-backed securities were 3.0 years based upon current prepayment assumptions.

Sales of available for sale securities resulted in gains and losses as follows (in thousands):

			Year Ended December 31,
			2020						2019						2018
Proceeds			$	384,507					$	1,211,718					$	745,643
Gross realized gains			9,976						14,996						7,117
Gross realized losses			(66)						(9,399)						(9,918)
Related federal and state income tax expense (benefit)			2,524						1,425						(713)

Debt Securities, Available for Sale, Unrealized Loss Position [Table Text Block]

Temporarily Impaired Available for Sale Securities

(In thousands)

						December 31, 2020
						Number of Securities						Less Than 12 Months												12 Months or Longer												Total
												Fair Value						Unrealized Loss						Fair Value						Unrealized Loss						Fair Value						Unrealized Loss
Available for sale:
Municipal securities						1						6,166						5						—						—						6,166						5
Mortgage-backed securities:
Residential agency						38						$	786,890					$	6,605					$	160,747					$	120					$	947,637					$	6,725
Commercial agency						37						350,506						1,587						277,627						494						628,133						2,081
Other debt securities						1						—						—						472						28						472						28
Total available for sale securities						77						$	1,143,562					$	8,197					$	438,846					$	642					$	1,582,408					$	8,839

						December 31, 2019
						Number of Securities						Less Than 12 Months												12 Months or Longer												Total
												Fair Value						Unrealized Loss						Fair Value						Unrealized Loss						Fair Value						Unrealized Loss
Available for sale:
Municipal securities						—						—						—						—						—						—						—
Mortgage-backed securities:
Residential agency						133						$	1,352,597					$	6,690					$	686,002					$	8,423					$	2,038,599					$	15,113
Commercial agency						69						830,047						4,238						210,877						907						1,040,924						5,145
Other debt securities						1						—						—						472						28						472						28
Total available for sale securities						203						$	2,182,644					$	10,928					$	897,351					$	9,358					$	3,079,995					$	20,286

Fair Value Option Securities [Table Text Block]

The fair value and net unrealized gain (loss) included in fair value option securities is as follows (in thousands):

						December 31, 2020												December 31, 2019
						Fair Value						Net Unrealized Gain (Loss)						Fair Value						Net Unrealized Gain (Loss)
U.S. Treasury						$	—					$	—					$	9,917					$	(48)
Residential agency mortgage-backed securities						114,982						4,463						1,088,660						14,109
Total						$	114,982					$	4,463					$	1,098,577					$	14,061

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