Shareholders' Equity - Summary of Required Regulatory Capital (Details) $ in Thousands	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Parent Company
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Risk-Based Capital Ratio (to risk-weighted assets), Amount	$ 1,200,885	$ 1,029,455
Tier 1 Capital (to risk-weighted assets), Amount	1,147,306	970,594
Common Equity Tier 1 Capital (to risk-weighted assets), Amount	1,075,656	899,225
Leverage (to adjusted average assets), Amount	$ 1,147,306	$ 970,594
Total Risk-Based Capital Ratio (to risk-weighted assets), Ratio	0.1821	0.1851
Tier 1 Capital (to risk-weighted assets), Ratio	0.1740	0.1746
Common Equity Tier 1 Capital (to risk-weighted assets), Ratio	16.31%	16.17%
Leverage (to adjusted average assets), Ratio	0.1168	0.1192
Total Risk-Based Capital Ratio (to risk-weighted assets), Minimum for Capital Adequacy Purpose, Amount	$ 527,630	$ 444,839
Tier 1 Capital (to risk-weighted assets), Minimum for Capital Adequacy Purpose, Amount	395,723	333,629
Common Equity Tier 1 Capital (to risk-weighted assets), Minimum for Capital, Adequacy Purpose, Amount	296,792	250,222
Leverage (to adjusted average assets), Minimum for Capital Adequacy Purpose, Amount	$ 392,763	$ 325,690
Total Risk-Based Capital Ratio (to risk-weighted assets), Minimum for Capital Adequacy Purpose, Ratio	0.0800	0.0800
Tier 1 Capital (to risk-weighted assets), Minimum for Capital Adequacy Purpose, Ratio	0.0600	0.0600
Common Equity Tier 1 Capital (to risk-weighted assets), Minimum for Capital, Adequacy Purpose, Ratio	4.50%	4.50%
Leverage (to adjusted average assets), Minimum for Capital Adequacy Purpose, Ratio	0.0400	0.0400
Seacoast National Bank (A Wholly Owned Bank Subsidiary)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Risk-Based Capital Ratio (to risk-weighted assets), Amount	$ 1,099,439	$ 956,592
Tier 1 Capital (to risk-weighted assets), Amount	1,045,860	897,731
Common Equity Tier 1 Capital (to risk-weighted assets), Amount	1,045,856	897,727
Leverage (to adjusted average assets), Amount	$ 1,045,860	$ 897,731
Total Risk-Based Capital Ratio (to risk-weighted assets), Ratio	0.1668	0.1721
Tier 1 Capital (to risk-weighted assets), Ratio	0.1586	0.1615
Common Equity Tier 1 Capital (to risk-weighted assets), Ratio	15.86%	16.15%
Leverage (to adjusted average assets), Ratio	0.1065	0.1103
Total Risk-Based Capital Ratio (to risk-weighted assets), Minimum for Capital Adequacy Purpose, Amount	$ 527,055	$ 444,617
Tier 1 Capital (to risk-weighted assets), Minimum for Capital Adequacy Purpose, Amount	395,291	333,463
Common Equity Tier 1 Capital (to risk-weighted assets), Minimum for Capital, Adequacy Purpose, Amount	296,468	250,097
Leverage (to adjusted average assets), Minimum for Capital Adequacy Purpose, Amount	$ 392,638	$ 325,523
Total Risk-Based Capital Ratio (to risk-weighted assets), Minimum for Capital Adequacy Purpose, Ratio	0.0800	0.0800
Tier 1 Capital (to risk-weighted assets), Minimum for Capital Adequacy Purpose, Ratio	0.0600	0.0600
Common Equity Tier 1 Capital (to risk-weighted assets), Minimum for Capital, Adequacy Purpose, Ratio	4.50%	4.50%
Leverage (to adjusted average assets), Minimum for Capital Adequacy Purpose, Ratio	0.0400	0.0400
Total Risk-Based Capital Ratio (to risk-weighted assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 658,819	$ 555,772
Tier 1 Capital (to risk-weighted assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	527,055	444,617
Common Equity Tier 1 Capital (to risk-weighted assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	428,232	361,252
Leverage (to adjusted average assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 490,798	$ 406,904
Total Risk-Based Capital Ratio (to risk-weighted assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	0.1000	0.1000
Tier 1 Capital (to risk-weighted assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	0.0800	0.0800
Common Equity Tier 1 Capital (to risk-weighted assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	6.50%	6.50%
Leverage (to adjusted average assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	0.0500	0.0500