Goodwill and Other Intangible Assets - Carrying Amounts of Goodwill by Operating Segments (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2024 USD ($)
Goodwill [Roll Forward]
Balance at January 1, 2024	$ 991,665
Additions to goodwill and other adjustments	0
Balance at June 30, 2024	991,665
Community Banks
Goodwill [Roll Forward]
Balance at January 1, 2024	988,898
Additions to goodwill and other adjustments	0
Balance at June 30, 2024	988,898
Insurance
Goodwill [Roll Forward]
Balance at January 1, 2024	2,767
Additions to goodwill and other adjustments	0
Balance at June 30, 2024	$ 2,767