Goodwill and Other Intangible Assets - Carrying Amounts of Goodwill by Operating Segments (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Goodwill [Roll Forward]
Balance at January 1	$ 988,898	$ 991,665
Additions to goodwill from The First merger	422,813	0
Goodwill, Written off Related to Sale of Business Unit	0	(2,767)
Balance at September 30	1,411,711	988,898
Community Banks
Goodwill [Roll Forward]
Balance at January 1	988,898	988,898
Additions to goodwill from The First merger	422,813	0
Goodwill, Written off Related to Sale of Business Unit	0	0
Balance at September 30	$ 1,411,711	988,898
Insurance
Goodwill [Roll Forward]
Balance at January 1		2,767
Additions to goodwill from The First merger		0
Goodwill, Written off Related to Sale of Business Unit		(2,767)
Balance at September 30		$ 0