Seacoast Banking Corporation of Florida (Parent Company Only) Financial Information - Summary of Statement of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Adjustments to reconcile net income to net cash provided by operating activities:
Net Income	$ 77,764	$ 98,739	$ 67,275
Net (increase) decrease in other assets	(35,555)	(5,614)	10,331
Net increase (decrease) in other liabilities	18,776	(4,206)	8,827
Net Cash Provided by Operating Activities	60,652	117,745	129,608
Cash Flows From Investing Activities
Net Cash Used in Investing Activities	(342,502)	(321,341)	(174,600)
Cash Flows From Financing Activities
Stock based employee benefit plans	(1,486)	(2,135)
Stock based employee benefit plans			979
Net Cash Provided by Financing Activities	561,407	212,176	51,439
Net increase in cash and cash equivalents	279,557	8,580	6,447
Cash and Cash Equivalents at Beginning of Year	124,531	115,951	109,504
Cash and Cash Equivalents at End of Year	404,088	124,531	115,951
Supplemental disclosure of cash flow information:
Cash paid during the period for interest	23,548	46,130	28,301
Parent Company
Adjustments to reconcile net income to net cash provided by operating activities:
Net Income	77,764	98,739	67,275
Equity in undistributed income of subsidiaries	(79,979)	(101,377)	(70,088)
Net (increase) decrease in other assets	1,772	(738)	(10,045)
Net increase (decrease) in other liabilities	256	265	(3,431)
Net Cash Provided by Operating Activities	(187)	(3,111)	(16,289)
Cash Flows From Investing Activities
Net cash paid for bank acquisition	(1,462)	0	(6,558)
Investment in unconsolidated subsidiary	0	(10)	0
Proceeds from sale of Visa Class B stock	0	0	21,333
Dividends from bank subsidiary	20,230	18,082	0
Increase in securities purchased under agreement to resell, maturing within 30 days, net	(17,095)	(12,849)	(421)
Net Cash Used in Investing Activities	1,673	5,223	14,354
Cash Flows From Financing Activities
Stock based employee benefit plans	(1,486)	(2,239)
Stock based employee benefit plans			978
Net Cash Provided by Financing Activities	(1,486)	(2,239)	978
Net increase in cash and cash equivalents	0	(127)	(957)
Cash and Cash Equivalents at Beginning of Year	70	197	1,154
Cash and Cash Equivalents at End of Year	70	70	197
Supplemental disclosure of cash flow information:
Cash paid during the period for interest	$ 1,992	$ 3,186	$ 2,936