Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2020

Fair Value Disclosures [Abstract]

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

The tables below summarize financial assets and financial liabilities measured at fair value on a recurring basis as of June 30, 2020 and December 31, 2019, segregated by the level of the valuation inputs within the fair value hierarchy of ASC Topic 820 utilized to measure fair value.

	Level 1 Inputs		Level 2 Inputs		Level 3 Inputs		Total Fair Value
June 30, 2020
Securities available for sale:
U.S. Treasury	$	1,163,635	$	—	$	—	$	1,163,635
Residential mortgage-backed securities	—		2,131,287		—		2,131,287
States and political subdivisions	—		7,269,495		—		7,269,495
Other	—		42,279		—		42,279
Trading account securities:
U.S. Treasury	24,495		—		—		24,495
Derivative assets:
Interest rate swaps, caps and floors	—		103,103		—		103,103
Commodity swaps and options	—		41,324		—		41,324
Foreign currency forward contracts	22		—		—		22
Derivative liabilities:
Interest rate swaps, caps and floors	—		40,008		—		40,008
Commodity swaps and options	—		40,560		—		40,560
Foreign currency forward contracts	11		—		—		11

December 31, 2019
Securities available for sale:
U.S. Treasury	$	1,948,133	$	—	$	—	$	1,948,133
Residential mortgage-backed securities	—		2,207,594		—		2,207,594
States and political subdivisions	—		7,070,997		—		7,070,997
Other	—		42,867		—		42,867
Trading account securities:
U.S. Treasury	24,298		—		—		24,298
Derivative assets:
Interest rate swaps, caps and floors	—		44,196		—		44,196
Commodity swaps and options	—		12,218		—		12,218
Foreign currency forward contracts	45		—		—		45
Derivative liabilities:
Interest rate swaps, caps and floors	—		20,197		—		20,197
Commodity swaps and options	—		11,677		—		11,677
Foreign currency forward contracts	33		—		—		33

Impaired Loans Remeasured And Reported At Fair Value Specific Valuation Allowance Allocation Method Of Underlying Collateral [Table Text Block]

The following table presents collateral dependent loans that were remeasured and reported at fair value through a specific allocation of the allowance for credit losses on loans based upon the fair value of the underlying collateral during the reported periods.

	Six Months Ended June 30, 2020				Six Months Ended June 30, 2019
	Level 2		Level 3		Level 2		Level 3
Carrying value before allocations	$	5,257	$	5,006	$	2,161	$	33,839
Specific (allocations) reversals of prior allocations	(731)		4,209		1,179		(3,623)
Fair value	$	4,526	$	9,215	$	3,340	$	30,216

Foreclosed Assets Remeasured and Reported at Fair Value

The following table presents foreclosed assets that were remeasured and reported at fair value during the reported periods:

	Six Months Ended June 30,
	2020		2019
Foreclosed assets remeasured at initial recognition:
Carrying value of foreclosed assets prior to remeasurement	$	—	$	616
Charge-offs recognized in the allowance for credit losses on loan	—		(50)
Fair value	$	—	$	566
Foreclosed assets remeasured subsequent to initial recognition:
Carrying value of foreclosed assets prior to remeasurement	$	328	$	—
Write-downs included in other non-interest expense	(231)		—
Fair value	$	97	$	—

Estimated Fair Values of Financial Instruments

The estimated fair values of financial instruments that are reported at amortized cost in our consolidated balance sheets, segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value, were as follows:

	June 30, 2020				December 31, 2019
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
Financial assets:
Level 2 inputs:
Cash and cash equivalents	$	6,599,568	$	6,599,568	$	3,788,181	$	3,788,181
Securities held to maturity	1,968,954		2,073,441		2,030,005		2,048,675
Cash surrender value of life insurance policies	189,091		189,091		187,156		187,156
Accrued interest receivable	176,522		176,522		183,850		183,850
Level 3 inputs:
Loans, net	17,721,876		17,914,646		14,618,165		14,654,615
Financial liabilities:
Level 2 inputs:
Deposits	32,679,096		32,685,609		27,639,564		27,641,255
Federal funds purchased and repurchase agreements	1,589,384		1,589,384		1,695,342		1,695,342
Junior subordinated deferrable interest debentures	136,328		137,115		136,299		137,115
Subordinated notes	98,943		112,500		98,865		89,077
Accrued interest payable	11,323		11,323		12,393		12,393