Goodwill and Intangible Assets (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) $ / loans Rate	Dec. 31, 2018 USD ($) $ / loans Rate	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Goodwill [Roll Forward]
Beginning goodwill	$ 236,347,000	$ 150,601,000
Ending goodwill	349,398,000	236,347,000	$ 150,601,000
Servicing Asset at Amortized Cost	22,963,000	21,396,000	21,945,000	$ 20,415,000
Servicing Asset at Amortized Cost, Additions	6,149,000	5,258,000	7,174,000
Amortization	(6,233,000)	(5,807,000)	(5,648,000)
Valuation Allowance for Impairment of Recognized Servicing Assets, Provisions (Recoveries)	$ 222,000	$ 0	(4,000)
Residential Mortgage Loans Serviced			2,810,000,000
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Prepayment Speed | Rate	13.72%	9.26%
Contractually Specified Servicing Fee, Late Fee, and Ancillary Fee Earned in Exchange for Servicing Financial Asset	$ 7,900,000	$ 7,500,000	7,100,000
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Cost to Service Loans | $ / loans	87.09	87.52
Finite-lived Intangible Assets [Roll Forward]
Beginning balance	$ 48,232,000	$ 51,151,000
Amortization	16,346,000	17,165,000
Ending balance	43,386,000	48,232,000	51,151,000
Finite-Lived Intangible Assets [Abstract]
Gross balance	154,507,000	143,007,000
Accumulated amortization	111,121,000	94,775,000
Carrying value	43,386,000	48,232,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2019		14,165,000
2020		10,850,000
2021		7,658,000
2022		5,056,000
2024 and subsequent		5,657,000
Other servicing rights	1,900,000	2,700,000
Biscayne Bancshares
Goodwill [Roll Forward]
Goodwill acquired	46,521,000
Finite-lived Intangible Assets [Roll Forward]
Intangible assets acquired	4,745,000
First South Bancorp
Goodwill [Roll Forward]
Goodwill acquired	13,896,000
Finite-lived Intangible Assets [Roll Forward]
Intangible assets acquired	2,268,000
Entegra Financial
Goodwill [Roll Forward]
Goodwill acquired	52,634,000
Ending goodwill	52,634,000
Servicing Asset at Amortized Cost, Additions	1,873,000	0	$ 0
Finite-lived Intangible Assets [Roll Forward]
Intangible assets acquired	4,487,000
HomeBancorp Inc.
Goodwill [Roll Forward]
Goodwill acquired		57,616,000
Finite-lived Intangible Assets [Roll Forward]
Intangible assets acquired	0	9,860,000
Capital Commerce Bancorp
Goodwill [Roll Forward]
Goodwill acquired		10,680,000
Finite-lived Intangible Assets [Roll Forward]
Intangible assets acquired	0	2,680,000
Palmetto Heritage Bancshares
Goodwill [Roll Forward]
Goodwill acquired		17,450,000
Finite-lived Intangible Assets [Roll Forward]
Intangible assets acquired	$ 0	$ 1,706,000
Conventional fixed loans
Goodwill [Roll Forward]
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Discount Rate | Rate	8.92%	9.69%
All loans and leases excluding conventional fixed loans [Member]
Goodwill [Roll Forward]
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Discount Rate | Rate	9.92%	10.69%
Minimum
Goodwill [Roll Forward]
Useful life (years)	5 years
Maximum
Goodwill [Roll Forward]
Useful life (years)	12 years
Core Deposit Intangibles
Goodwill [Roll Forward]
Useful life (years)	10 years 2 months 12 days