BUSINESS COMBINATIONS - fair value of the assets purchased, including goodwill, and liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Nov. 03, 2017	Oct. 20, 2017	Apr. 07, 2017	Dec. 31, 2016	Jun. 03, 2016	Mar. 11, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets:
Loans, net						$ 314,000
Goodwill	$ 147,578				$ 64,649			$ 25,211	$ 25,309
Liabilities:
Deposits						63,000
Total liabilities assumed	$ 16,000
Floridian Financial Group [Member]
Assets:
Other assets							$ 417,000
Floridian Financial Group [Member] | Measurement Period Adjustments [Member]
Assets:
Cash							0
Investment securities							95
Loans, net							(2,112)
Fixed assets							(628)
Core deposit intangibles							0
Goodwill							1,647
Other assets							998
Total assets acquired							0
Liabilities:
Deposits							0
Other liabilities							0
Total liabilities assumed							0
Floridian Financial Group [Member] | Scenario, Previously Reported [Member]
Assets:
Cash							28,243
Investment securities							66,912
Loans, net							268,249
Fixed assets							7,801
Core deposit intangibles							3,375
Goodwill							29,985
Other assets							12,879
Total assets acquired							417,444
Liabilities:
Deposits							337,341
Other liabilities							2,492
Total liabilities assumed							339,833
Floridian Financial Group [Member] | Restatement Adjustment [Member]
Assets:
Cash							28,243
Investment securities							67,007
Loans, net							266,137
Fixed assets							7,173
Core deposit intangibles							3,375
Goodwill							31,632
Other assets							13,877
Total assets acquired							417,444
Liabilities:
Deposits							337,341
Other liabilities							2,492
Total liabilities assumed							$ 339,833
BMO Harris Bank [Member] | Measurement Period Adjustments [Member]
Assets:
Cash						0
Loans, net						0
Fixed assets						0
Core deposit intangibles						(135)
Goodwill						163
Other assets						(28)
Total assets acquired						0
Liabilities:
Deposits						0
Other liabilities						0
Total liabilities assumed						0
BMO Harris Bank [Member] | Scenario, Previously Reported [Member]
Assets:
Cash						234,094
Loans, net						62,671
Fixed assets						3,715
Core deposit intangibles						5,223
Goodwill						7,645
Other assets						952
Total assets acquired						314,300
Liabilities:
Deposits						314,248
Other liabilities						52
Total liabilities assumed						314,300
BMO Harris Bank [Member] | Restatement Adjustment [Member]
Assets:
Cash						234,094
Loans, net						62,671
Fixed assets						3,715
Core deposit intangibles						5,088
Goodwill						7,808
Other assets						924
Total assets acquired						314,300
Liabilities:
Deposits						314,248
Other liabilities						52
Total liabilities assumed						$ 314,300
Gulf Shore Banc shares Inc [Member]
Assets:
Other assets				$ 358,000
Gulf Shore Banc shares Inc [Member] | Measurement Period Adjustments [Member]
Assets:
Cash				0
Time deposits with other banks				0
Investment securities				0
Loans, net				0
Fixed assets				0
Other real estate owned (OREO)				0
Core deposit intangibles				0
Goodwill				0
Other assets				0
Total assets acquired				0
Liabilities:
Deposits				0
Other liabilities				0
Total liabilities assumed				0
Gulf Shore Banc shares Inc [Member] | Scenario, Previously Reported [Member]
Assets:
Cash				38,267
Time deposits with other banks				17,273
Investment securities				21
Loans, net				250,876
Fixed assets				1,307
Other real estate owned (OREO)				13
Core deposit intangibles				3,927
Goodwill				37,098
Other assets				8,867
Total assets acquired				357,649
Liabilities:
Deposits				285,350
Other liabilities				1,382
Total liabilities assumed				286,732
Gulf Shore Banc shares Inc [Member] | Restatement Adjustment [Member]
Assets:
Cash				38,267
Time deposits with other banks				17,273
Investment securities				21
Loans, net				250,876
Fixed assets				1,307
Other real estate owned (OREO)				13
Core deposit intangibles				3,927
Goodwill				37,098
Other assets				8,867
Total assets acquired				357,649
Liabilities:
Deposits				285,350
Other liabilities				1,382
Total liabilities assumed				$ 286,732
NorthStar Bank [Member]
Assets:
Other assets			$ 216,000
NorthStar Bank [Member] | Scenario, Previously Reported [Member]
Assets:
Cash			5,485
Investment securities			56,123
Loans, net			136,832
Fixed assets			2,637
Core deposit intangibles			1,275
Goodwill			12,404
Other assets			1,522
Total assets acquired			216,278
Liabilities:
Deposits			182,443
Other liabilities			980
Total liabilities assumed			$ 183,423
Palm Beach Community Bank [Member]
Assets:
Cash		$ 9,301
Investment securities		22,098
Loans, net		272,090
Fixed assets		7,641
Core deposit intangibles		2,523
Goodwill		33,428
Other assets		9,909
Total assets acquired		356,990
Liabilities:
Deposits		268,633
Other liabilities		16,351
Total liabilities assumed		$ 284,984