Fair Value Disclosures (Tables)

12 Months Ended

Dec. 31, 2021

Fair Value Disclosures [Abstract]

Financial Assets and Financial Liabilities Measured at Fair Value on Recurring Basis

The following table summarizes the Company’s available-for-sale securities, loans held-for-sale, and derivatives which are measured at fair value on a recurring basis as of December 31, 2021 and 2020 segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value (in thousands):

December 31, 2021	Level 1 Inputs		Level 2 Inputs			Level 3 Inputs		Total Fair Value
Available-for-sale investment securities:
U.S. Treasury securities	$	126,841	$	—		$	—	$	126,841
Obligations of state and political subdivisions		—		2,753,471			—		2,753,471
Corporate bonds		—		63,868			—		63,868
Residential mortgage-backed securities		—		3,259,449			—		3,259,449
Commercial mortgage-backed securities		—		365,120			—		365,120
Other securities		4,430		—			—		4,430
Total	$	131,271	$	6,441,908		$	—	$	6,573,179
Loans held-for-sale	$	—	$	34,122		$	—	$	34,122
IRLCs	$	—	$	1,279		$	—	$	1,279
Forward mortgage-backed securities traded	$	—	$	(147	)	$	—	$	(147	)

December 31, 2020	Level 1 Inputs		Level 2 Inputs			Level 3 Inputs		Total Fair Value
Available-for-sale investment securities:
Obligations of state and political subdivisions	$	—	$	2,426,876		$	—	$	2,426,876
Residential mortgage-backed securities		—		1,472,280			—		1,472,280
Commercial mortgage-backed securities		—		489,316			—		489,316
Other securities		4,557		—			—		4,557
Total	$	4,557	$	4,388,472		$	—	$	4,393,029
Loans held-for-sale	$	—	$	79,585		$	—	$	79,585
IRLCs	$	—	$	4,618		$	—	$	4,618
Forward mortgage-backed securities traded	$	—	$	(1,560	)	$	—	$	(1,560	)

Summary of Loans Held-for-Sale at Fair Value

The following table summarizes the Company’s loans held-for-sale at fair value and the net unrealized gains as of the balance sheet dates shown below (in thousands):

	December 31,
	2021		2020
Unpaid principal balance on loans held-for-sale	$	33,200	$	76,602
Net unrealized gains on loans held-for-sale		922		2,983
Loans held-for-sale at fair value	$	34,122	$	79,585

Summary of Gain Loss on Sale of Mortgage Loans

The following table summarizes the Company’s gains on sale and fees of mortgage loans for the years ended December 31, 2021, 2020 and 2019 (in thousands):

	Years ended December 31,
	2021			2020			2019
Realized gain on sale and fees on mortgage loans*	$	37,091		$	39,378		$	17,748
Change in fair value on loans held-for-sale and IRLCs		(5,259	)		5,900			145
Change in forward mortgage-backed securities trades		1,413			(1,406	)		251
Total gain on sale of mortgage loans	$	33,245		$	43,872		$	18,144

* This includes gain on loans held-for-sale carried under the fair value method and lower of cost or market.

Schedule of Estimated Fair Values and Carrying Values of All Financial Instruments

The estimated fair values and carrying values of all financial instruments under current authoritative guidance at December 31, 2021 and 2020, were as follows (in thousands):

	2021						2020
	Carrying			Estimated			Carrying			Estimated			Fair Value
	Value			Fair Value			Value			Fair Value			Hierarchy
Cash and due from banks	$	205,053		$	205,053		$	211,113		$	211,113		Level 1
Interest-bearing demand deposits in banks		323,535			323,535			517,971			517,971		Level 1
Available-for-sale securities		6,573,179			6,573,179			4,393,029			4,393,029		Levels 1 and 2
Loans held-for-investment, net of allowance for    credit losses		5,325,507			5,335,791			5,104,499			5,109,885		Level 3
Loans held-for-sale		37,810			37,844			83,969			84,233		Level 2
Accrued interest receivable		57,169			57,169			53,433			53,433		Level 2
Deposits with stated maturities		461,415			462,312			475,542			477,218		Level 2
Deposits with no stated maturities		10,105,073			10,105,073			8,200,275			8,200,275		Level 1
Borrowings		671,152			671,152			430,093			430,093		Level 2
Accrued interest payable		221			221			377			377		Level 2
IRLCs		1,279			1,279			4,618			4,618		Level 2
Forward mortgage-backed securities trades		(147	)		(147	)		(1,560	)		(1,560	)	Level 2