BUSINESS COMBINATIONS - fair value of the assets purchased, including goodwill, and liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Jun. 03, 2016	Mar. 11, 2016
Assets:
Loans, net			$ 314,000
Goodwill	$ 64,649	$ 64,649
Liabilities:
Deposits			63,000
Bank shares, Inc [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
Bank shares, Inc [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
Bank shares, Inc [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