Goodwill and Other Intangible Assets - Carrying Amounts of Goodwill by Operating Segments (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022 USD ($)
Goodwill [Roll Forward]
Balance at January 1, 2022	$ 939,683
Additions to goodwill from the Southeastern Commercial Finance, LLC acquisition	6,608
Balance at March 31, 2022	946,291
Community Banks
Goodwill [Roll Forward]
Balance at January 1, 2022	936,916
Additions to goodwill from the Southeastern Commercial Finance, LLC acquisition	6,608
Balance at March 31, 2022	943,524
Insurance
Goodwill [Roll Forward]
Balance at January 1, 2022	2,767
Additions to goodwill from the Southeastern Commercial Finance, LLC acquisition	0
Balance at March 31, 2022	$ 2,767