LOANS - Loans Evaluated for Impairment (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Loans receivable: balance at end of period
Total loans	$ 8,376,417	$ 8,299,338
Commercial Real Estate
Loans receivable: balance at end of period
Total loans	3,266,737	3,264,742
Residential Mortgages
Loans receivable: balance at end of period
Total loans	2,181,807	2,102,807
Consumer Loans
Loans receivable: balance at end of period
Total loans	1,108,899	1,127,850
Business Activities Loans
Loans receivable: balance at end of period
Individually evaluated for impairment	44,318	43,365
Collectively evaluated for impairment	6,238,360	6,068,833
Total loans	6,282,678	6,112,198
Business Activities Loans \| Commercial Real Estate
Loans receivable: balance at end of period
Individually evaluated for impairment	33,094	33,732
Collectively evaluated for impairment	2,248,409	2,183,975
Total loans	2,281,503	2,217,707
Business Activities Loans \| Commercial and industrial loans
Loans receivable: balance at end of period
Individually evaluated for impairment	6,913	5,761
Collectively evaluated for impairment	1,188,729	1,176,808
Total loans	1,195,642	1,182,569
Business Activities Loans \| Residential Mortgages
Loans receivable: balance at end of period
Individually evaluated for impairment	2,466	3,872
Collectively evaluated for impairment	1,904,247	1,809,329
Total loans	1,906,713	1,813,201
Business Activities Loans \| Consumer Loans
Loans receivable: balance at end of period
Individually evaluated for impairment	1,845	0
Collectively evaluated for impairment	896,975	898,721
Total loans	898,820	898,721
Acquired Loans
Loans receivable: balance at end of period
Individually evaluated for impairment	9,958	7,309
Purchased credit-impaired loans	93,645	97,344
Collectively evaluated for impairment	1,990,136	2,082,487
Total loans	2,093,739	2,187,140
Acquired Loans \| Commercial Real Estate
Loans receivable: balance at end of period
Individually evaluated for impairment	5,424	4,244
Purchased credit-impaired loans	47,885	53,302
Collectively evaluated for impairment	931,925	989,489
Total loans	985,234	1,047,035
Acquired Loans \| Commercial and industrial loans
Loans receivable: balance at end of period
Individually evaluated for impairment	745	421
Purchased credit-impaired loans	36,461	34,629
Collectively evaluated for impairment	586,126	586,320
Total loans	623,332	621,370
Acquired Loans \| Residential Mortgages
Loans receivable: balance at end of period
Individually evaluated for impairment	2,695	2,617
Purchased credit-impaired loans	6,903	6,974
Collectively evaluated for impairment	265,496	280,015
Total loans	275,094	289,606
Acquired Loans \| Consumer Loans
Loans receivable: balance at end of period
Individually evaluated for impairment	1,094	27
Purchased credit-impaired loans	2,396	2,439
Collectively evaluated for impairment	206,589	226,663
Total loans	$ 210,079	$ 229,129

Financing Receivable, Purchased Credit-Impaired Loans

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- Definition

The balance of financing receivables that were collectively evaluated for impairment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

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- Definition

The balance of financing receivables that were individually evaluated for impairment.

+ References

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- Definition

Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5074-111524

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- References

No definition available.

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