Investment Securities - Held-to-Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2025		Dec. 31, 2024	Dec. 31, 2023
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	$ 2,309,331		$ 2,307,649
Interest Receivable	11,400		12,600
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, after Allowance for Credit Loss	2,308,636	[1]	2,306,149
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	2,052	[1]	35
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(64,162)	[1]	(149,490)
Debt Securities, Held-to-maturity, Fair Value	2,246,526	[1]	2,156,694
Debt Securities, Held-to-Maturity, Allowance for Credit Loss, Excluding Accrued Interest	(695)	[1]	(1,500)	$ (1,500)
US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	1,237,792		1,251,364
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, after Allowance for Credit Loss	1,237,772		1,251,224
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	2,052		35
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(20,713)		(54,799)
Debt Securities, Held-to-maturity, Fair Value	1,219,111		1,196,460
Debt Securities, Held-to-Maturity, Allowance for Credit Loss, Excluding Accrued Interest	(20)		(140)
Commercial Mortgage Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	447,283		440,476
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, after Allowance for Credit Loss	447,283		440,476
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0		0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(19,645)		(37,840)
Debt Securities, Held-to-maturity, Fair Value	427,638		402,636
Debt Securities, Held-to-Maturity, Allowance for Credit Loss, Excluding Accrued Interest	0		0
Mortgage-backed Securities, Issued by Private Enterprises
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	360,382		355,342
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, after Allowance for Credit Loss	360,382		355,342
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0		0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(9,606)		(26,226)
Debt Securities, Held-to-maturity, Fair Value	350,776		329,116
Debt Securities, Held-to-Maturity, Allowance for Credit Loss, Excluding Accrued Interest	0		0
US Treasury Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	193,022		189,985
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, after Allowance for Credit Loss	193,022		189,985
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0		0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(7,934)		(16,702)
Debt Securities, Held-to-maturity, Fair Value	185,088
Debt Securities, Held-to-Maturity, Allowance for Credit Loss, Excluding Accrued Interest	0		0
Corporate Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	70,852		70,482
Interest Receivable	13,400		13,400
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, after Allowance for Credit Loss	70,177		69,122
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0		0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(6,264)		(13,923)
Debt Securities, Held-to-maturity, Fair Value	63,913		55,199
Debt Securities, Held-to-Maturity, Allowance for Credit Loss, Excluding Accrued Interest	$ (675)		$ (1,360)

[1] Excludes accrued interest receivable of $13.4 million at December 31, 2025 which is recorded in "Other assets" on the consolidated balance shee