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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 11
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481830/320-10-45-11

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-9

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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-12

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-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 11
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-11

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Investment Securities - Amortized cost and fair value by contractual maturity (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2025	Mar. 31, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Amortized Cost
Due after one year through five years	$ 94,797			$ 94,797
Due after five years through ten years	381,000			381,000
Due after ten years	1,620,930			1,620,930
Total	2,096,727			2,096,727		$ 2,254,670
Fair Value
Due after one year through five years	87,406			87,406
Due after five years through ten years	337,485			337,485
Due after ten years	1,340,596			1,340,596
Fair Value	1,765,487			1,765,487		1,834,527
Amortized Cost
Due in one year or less	34,325			34,325
Due after one year through five years	323,617			323,617
Due after five years through ten years	800,111			800,111
Due after ten years	5,310,262			5,310,262
Amortized Cost	6,468,315			6,468,315		5,129,216
Fair Value
Due in one year or less	34,214			34,214
Due after one year through five years	322,072			322,072
Due after five years through ten years	744,473			744,473
Due after ten years	4,942,041			4,942,041
Fair Value	6,042,800			6,042,800		$ 4,320,593
Information with respect to sales of held-to-maturity
Proceeds from sales of investment securities held to maturity	0		$ 0	0	$ 0
Information with respect to sales of available-for-sale securities
Sale proceeds				2,874,110
Gross realized gains				8,892
Gross realized losses				(237,703)
Net realized losses				(228,811)
Sold securities	$ 0	$ 1,800,000	$ 0		$ 0
Realized gains or losses		$ 0
Sales of Securities Acquired from Independent
Information with respect to sales of available-for-sale securities
Sale proceeds				1,279,717
Investment Securities Sales
Information with respect to sales of available-for-sale securities
Sale proceeds				1,594,393
Gross realized gains				8,892
Gross realized losses				(237,703)
Net realized losses				$ (228,811)