Business Combinations - Additional Information (Details) $ / shares in Units, $ in Thousands					12 Months Ended
	Oct. 19, 2018 USD ($) branch $ / shares	Nov. 03, 2017 USD ($) branch $ / shares	Oct. 20, 2017 USD ($) branch $ / shares	Apr. 07, 2017 USD ($) branch $ / shares	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Business Acquisition [Line Items]
Goodwill, nondeductible for tax purposes					$ 205,286	$ 204,753	$ 147,578	$ 64,649
Acquisition costs					$ 1,000	$ 9,700	$ 12,900
Gulf Shore Banc shares Inc
Business Acquisition [Line Items]
Number of branches acquired | branch				3
Total assets acquired				$ 357,649
Loans, net				250,876
Deposits acquired				$ 285,350
Percentage of common stock acquired				100.00%
Cash portion, cash per share for common stock converted (in dollars per share) | $ / shares				$ 1.47
Common stock portion, number of Seacoast stock for each share of stock converted (in shares)				0.4807
Multiplied by common stock price per share (in dollars per share) | $ / shares				$ 23.94
Goodwill, nondeductible for tax purposes				$ 37,098
NorthStar Bank
Business Acquisition [Line Items]
Number of branches acquired | branch			3
Percentage of common stock acquired			100.00%
Cash portion, cash per share for common stock converted (in dollars per share) | $ / shares			$ 2.40
Common stock portion, number of Seacoast stock for each share of stock converted (in shares)			0.5605
Multiplied by common stock price per share (in dollars per share) | $ / shares			$ 24.92
Palm Beach Community Bank
Business Acquisition [Line Items]
Number of branches acquired | branch		4
Percentage of common stock acquired		100.00%
Cash portion, cash per share for common stock converted (in dollars per share) | $ / shares		$ 6.26
Common stock portion, number of Seacoast stock for each share of stock converted (in shares)		0.9240
Multiplied by common stock price per share (in dollars per share) | $ / shares		$ 24.31
First Green Bancorp, Inc.
Business Acquisition [Line Items]
Number of branches acquired | branch	7
Percentage of common stock acquired	100.00%
Common stock portion, number of Seacoast stock for each share of stock converted (in shares)	0.7324
Multiplied by common stock price per share (in dollars per share) | $ / shares	$ 26.87
Goodwill, nondeductible for tax purposes	$ 56,700
As Adjusted | NorthStar Bank
Business Acquisition [Line Items]
Total assets acquired			$ 216,278
Loans, net			136,832
Deposits acquired			182,443
Goodwill, nondeductible for tax purposes			$ 12,305
As Adjusted | Palm Beach Community Bank
Business Acquisition [Line Items]
Total assets acquired		$ 356,990
Loans, net		270,318
Deposits acquired		268,633
Goodwill, nondeductible for tax purposes		$ 34,504
As Adjusted | First Green Bancorp, Inc.
Business Acquisition [Line Items]
Total assets acquired	817,386
Loans, net	631,497
Deposits acquired	624,289
Goodwill, nondeductible for tax purposes	$ 56,731