Shareholders' Equity - Summary of Required Regulatory Capital (Details) - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015
Parent Company [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital (to risk-weighted assets), Amount		$ 432,058	$ 383,039
Total Capital (to risk-weighted assets), Ratio		13.25%	16.01%
Total Capital (to risk-weighted assets), Minimum for Capital Adequacy Purpose, Amount	[1]	$ 260,790	$ 191,413
Total Capital (to risk-weighted assets), Minimum for Capital Adequacy Purpose, Ratio	[1]	8.00%	8.00%
Tier 1 Capital (to risk-weighted assets), Amount		$ 408,596	$ 363,873
Tier 1 Capital (to risk-weighted assets), Ratio		12.53%	15.21%
Tier 1 Capital (to risk-weighted assets), Minimum for Capital Adequacy Purpose, Amount	[1]	$ 195,592	$ 143,560
Tier 1 Capital (to risk-weighted assets), Minimum for Capital Adequacy Purpose, Ratio	[1]	6.00%	6.00%
Common Equity Tier 1 Capital (to risk-weighted assets), Amount		$ 351,769	$ 317,004
Common Equity Tier 1 Capital (to risk-weighted assets), Ratio		10.79%	13.25%
Common Equity Tier 1 Capital (to risk-weighted assets), Minimum for Capital, Adequacy Purpose, Amount	[1]	$ 146,694	$ 107,670
Common Equity Tier 1 Capital (to risk-weighted assets), Minimum for Capital, Adequacy Purpose, Ratio	[1]	4.50%	4.50%
Trust preferred securities issued		$ 408,596	$ 363,873
Tier 1 Capital (to adjusted average assets), Ratio		9.15%	10.70%
Tier 1 Capital (to adjusted average assets), Minimum for Capital Adequacy Purpose, Amount		$ 178,656	$ 136,009	[1]
Tier 1 Capital (to adjusted average assets), Minimum for Capital Adequacy Purpose, Ratio		4.00%	4.00%	[1]
Seacoast Bank (A Wholly Owned Bank Subsidiary) [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital (to risk-weighted assets), Amount		$ 415,147	$ 337,259
Total Capital (to risk-weighted assets), Ratio		12.75%	14.11%
Total Capital (to risk-weighted assets), Minimum for Capital Adequacy Purpose, Amount	[1]	$ 260,491	$ 191,240
Total Capital (to risk-weighted assets), Minimum for Capital Adequacy Purpose, Ratio	[1]	8.00%	8.00%
Tier 1 Capital (to risk-weighted assets), Amount		$ 391,685	$ 318,093
Tier 1 Capital (to risk-weighted assets), Ratio		12.03%	13.31%
Tier 1 Capital (to risk-weighted assets), Minimum for Capital Adequacy Purpose, Amount	[1]	$ 195,368	$ 143,430
Tier 1 Capital (to risk-weighted assets), Minimum for Capital Adequacy Purpose, Ratio	[1]	6.00%	6.00%
Common Equity Tier 1 Capital (to risk-weighted assets), Amount		$ 391,685	$ 318,093
Common Equity Tier 1 Capital (to risk-weighted assets), Ratio		12.03%	13.31%
Common Equity Tier 1 Capital (to risk-weighted assets), Minimum for Capital, Adequacy Purpose, Amount	[1]	$ 146,526	$ 107,572
Common Equity Tier 1 Capital (to risk-weighted assets), Minimum for Capital, Adequacy Purpose, Ratio	[1]	4.50%	4.50%
Trust preferred securities issued		$ 391,685	$ 318,093
Tier 1 Capital (to adjusted average assets), Ratio		8.78%	9.36%
Tier 1 Capital (to adjusted average assets), Minimum for Capital Adequacy Purpose, Amount		$ 178,501	$ 135,929	[1]
Tier 1 Capital (to adjusted average assets), Minimum for Capital Adequacy Purpose, Ratio		4.00%	4.00%	[1]
Total Capital (to risk-weighted assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount		$ 325,987	$ 239,050
Total Capital (to risk-weighted assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio		10.00%	10.00%
Tier 1 Capital (to risk-weighted assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount		$ 260,790	$ 191,240
Tier 1 Capital (to risk-weighted assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio		8.00%	8.00%
Tier 1 Capital (to adjusted average assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount		$ 223,320	$ 169,911
Tier 1 Capital (to adjusted average assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio		5.00%	5.00%
Common Equity Tier 1 Capital (to risk-weighted assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount		$ 211,892	$ 155,382
Common Equity Tier 1 Capital (to risk-weighted assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio		6.50%	6.50%

[1] Excludes new capital conservation buffer of 0.625% the Company is subject to, which if not exceeded may constrain dividends, equity repurchases and compensation.