Employee Benefit Plans (Present Value of Accrued Liability) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	May 01, 2019	Apr. 02, 2019	Oct. 02, 2018
Present Value Of Accrued Liability [Roll Forward]
Benefit expense and interest cost	$ (1,582)	$ 4,572	$ 7,255
Interest cost	$ 37,260	$ 34,733	35,593
Discount rate	3.46%	4.38%
Executives Directors And Officer Of Acquired Entities
Present Value Of Accrued Liability [Roll Forward]
Present value of accrued liability as of January 1	$ 34,063	$ 37,299
Benefit expense and interest cost	3,970	535
Benefits paid	4,681	4,579
Present value of accrued liability as of December 31	45,295	34,063	$ 37,299
Biscayne Bancshares
Present Value Of Accrued Liability [Roll Forward]
Liability assumed	1,138	0			$ 956,756
First South Bancorp
Present Value Of Accrued Liability [Roll Forward]
Liability assumed	1,067	0		$ 215,561
Entegra
Present Value Of Accrued Liability [Roll Forward]
Liability assumed	9,738	0
Capital Commerce Bancorp
Present Value Of Accrued Liability [Roll Forward]
Liability assumed	$ 0	$ 808				$ 204,500