Business Combinations - Purchase Price (Details) $ / shares in Units, $ in Thousands	Nov. 03, 2017 USD ($) $ / shares shares	Oct. 20, 2017 USD ($) $ / shares shares	Apr. 07, 2017 USD ($) $ / shares shares
Gulf Shore Banc shares Inc
Business Acquisition [Line Items]
Value of shares exchanged for cash			$ 8,034
Number of shares outstanding (in shares) | shares			5,464
Common stock portion, number of Seacoast stock for each share of stock converted (in shares)			0.4807
Number of shares of Seacoast common stock issued (in shares) | shares			2,627
Multiplied by common stock price per share (in dollars per share) | $ / shares			$ 23.94
Value of common stock issued			$ 62,883
Total purchase price			$ 70,917
NorthStar Bank
Business Acquisition [Line Items]
Value of shares exchanged for cash		$ 4,701
Number of shares outstanding (in shares) | shares		1,958
Common stock portion, number of Seacoast stock for each share of stock converted (in shares)		0.5605
Number of shares of Seacoast common stock issued (in shares) | shares		1,098
Multiplied by common stock price per share (in dollars per share) | $ / shares		$ 24.92
Value of common stock issued		$ 27,353
Cash paid for NorthStar Banking vested Corporation stock options		801
Total purchase price		$ 32,855
Palm Beach Community Bank
Business Acquisition [Line Items]
Value of shares exchanged for cash	$ 15,694
Number of shares outstanding (in shares) | shares	2,507
Common stock portion, number of Seacoast stock for each share of stock converted (in shares)	0.924
Number of shares of Seacoast common stock issued (in shares) | shares	2,316
Multiplied by common stock price per share (in dollars per share) | $ / shares	$ 24.31
Value of common stock issued	$ 56,312
Total purchase price	$ 72,006