Securities, Held to Maturity (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Held-to-maturity securities, fair value to amortized cost [Abstract]
Amortized cost	$ 895,005		$ 733,210
Unrealized gains	762		10,040
Unrealized losses	44,132		7,990
Estimated fair value	851,635		735,260
Allowance for credit losses on HTM securities	0		0
Transactions of HTM securities [Abstract]
Gains from calls on HTM securities	4	$ 15
Asset Pledged as Collateral [Member] \| Public Deposits or Other Purposes [Member]
Securities pledged [Abstract]
AFS and HTM securities	1,800,000		1,600,000
Asset Pledged as Collateral [Member] \| Securities Sold under Repurchase Agreements [Member]
Securities pledged [Abstract]
AFS and HTM securities	144,900		162,100
Federal Agency [Member]
Held-to-maturity securities, fair value to amortized cost [Abstract]
Amortized cost	100,000		100,000
Unrealized gains	0		0
Unrealized losses	10,872		4,365
Estimated fair value	89,128		95,635
Mortgage-Backed, Government Sponsored Enterprises [Member]
Held-to-maturity securities, fair value to amortized cost [Abstract]
Amortized cost	269,153		161,462
Unrealized gains	137		2,232
Unrealized losses	16,499		1,319
Estimated fair value	252,791		162,375
Mortgage-Backed, U.S. Government Agency Securities [Member]
Held-to-maturity securities, fair value to amortized cost [Abstract]
Amortized cost	7,425		9,112
Unrealized gains	50		514
Unrealized losses	6		0
Estimated fair value	7,469		9,626
Collateralized Mortgage Obligations, Government-Sponsored Enterprises [Member]
Held-to-maturity securities, fair value to amortized cost [Abstract]
Amortized cost	111,254		94,342
Unrealized gains	105		1,932
Unrealized losses	2,722		129
Estimated fair value	108,637		96,145
Collateralized Mortgage Obligations, U.S. Government Agency Securities [Member]
Held-to-maturity securities, fair value to amortized cost [Abstract]
Amortized cost	74,596		44,473
Unrealized gains	76		336
Unrealized losses	3,755		674
Estimated fair value	70,917		44,135
State & Municipal [Member]
Held-to-maturity securities, fair value to amortized cost [Abstract]
Amortized cost	332,577		323,821
Unrealized gains	394		5,026
Unrealized losses	10,278		1,503
Estimated fair value	$ 322,693		$ 327,344

Gains from calls (requests of early payments) on debt securities which are classified as held-to-maturity securities.

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Amount, after allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), investment in debt security measured at amortized cost (held-to-maturity), and investment in debt security measured at fair value with change in fair value recognized in net income (trading).

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Amount of allowance for credit loss for debt security measured at amortized cost (held-to-maturity).

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Amount, after allowance for credit loss, of investment in debt security measured at amortized cost (held-to-maturity).

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Amount of accumulated unrecognized gain on investment in debt security measured at amortized cost (held-to-maturity).

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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity).

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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