Seacoast Banking Corporation of Florida (Parent Company Only) Financial Information - Summary of Statement of Cash Flows (Details) - USD ($) $ in Thousands		1 Months Ended		12 Months Ended
	Feb. 21, 2017	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Adjustments to reconcile net income to net cash provided by operating activities:
Net Income				$ 67,275	$ 42,865	$ 29,202
Gain on sale of Visa Class B stock		$ (15,200)		0	(15,153)	0
Net increase (decrease) in other assets				10,051	(5,506)	(11,573)
Net increase (decrease) in other liabilities				8,827	(21,432)	2,979
Net Cash Provided by Operating Activities				129,608	48,909	62,007
Cash Flows From Investing Activities
Purchase of Visa Class B stock			$ (6,200)	0	(6,180)	0
Proceeds from sale of Visa Class B stock				21,333	0	0
Net Cash Used in Investing Activities				(174,600)	(245,576)	(511,785)
Cash Flows From Financing Activities
Issuance of common stock, net of related expense	$ 56,700			0	55,641	0
Net Cash Provided by Financing Activities				51,439	196,527	423,355
Net increase (decrease) in cash and cash equivalents				6,447	(140)	(26,423)
Cash and cash equivalents at beginning of year				109,504	109,644	136,067
Cash and Cash Equivalents at End of Year		109,504		115,951	109,504	109,644
Supplemental disclosure of cash flow information:
Cash paid during the period for interest				28,301	15,125	7,855
Parent Company
Adjustments to reconcile net income to net cash provided by operating activities:
Net Income				67,275	42,865	29,202
Equity in undistributed income of subsidiaries				(70,088)	(33,694)	(30,626)
Gain on sale of Visa Class B stock				0	(15,153)	0
Net increase (decrease) in other assets				(10,045)	1,415	(12)
Net increase (decrease) in other liabilities				(3,431)	4,005	12
Net Cash Provided by Operating Activities				(16,289)	(562)	(1,424)
Cash Flows From Investing Activities
Net cash paid for bank acquisition				(6,558)	(27,862)	(28,905)
Investment in unconsolidated subsidiary				0	0	(200)
Purchase of Visa Class B stock				0	(6,180)	0
Proceeds from sale of Visa Class B stock				21,333	0	0
(Increase) decrease in securities purchased under agreement to resell, maturing within 30 days, net				(421)	(20,475)	30,647
Net Cash Used in Investing Activities				14,354	(54,517)	1,542
Cash Flows From Financing Activities
Issuance of common stock, net of related expense				0	55,641	0
Stock based employment benefit plans				978	(56)	166
Net Cash Provided by Financing Activities				978	55,585	166
Net increase (decrease) in cash and cash equivalents				(957)	506	284
Cash and cash equivalents at beginning of year				1,154	648	364
Cash and Cash Equivalents at End of Year		$ 1,154		197	1,154	648
Supplemental disclosure of cash flow information:
Cash paid during the period for interest				$ 2,936	$ 2,205	$ 1,824