FAIR VALUE DISCLOSURES - Summary of Financial Assets and Liabilities Measure at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets
Investment securities available-for-sale	$ 2,850,502	$ 2,779,255
Derivative Asset	148,071	29,189
Liabilities
Derivative liabilities	148,101	29,188
Fair Value, Measurements, Recurring
Assets
Investment securities available-for-sale	2,850,502	2,779,255
Derivative Asset		29,543
Total	2,998,686	2,808,798
Liabilities
Derivative liabilities		29,336
Total	148,551
Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 1
Assets
Investment securities available-for-sale	100	97
Derivative Asset		0
Total	100	97
Liabilities
Derivative liabilities		0
Total	0
Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 2
Assets
Investment securities available-for-sale	2,840,539	2,764,443
Derivative Asset		29,543
Total	2,988,723	2,793,986
Liabilities
Derivative liabilities		29,336
Total	148,551
Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 3
Assets
Investment securities available-for-sale	9,863	14,715
Derivative Asset		0
Total	9,863	14,715
Liabilities
Derivative liabilities		$ 0
Total	0
Interest Rate Contract [Member] \| Fair Value, Measurements, Recurring
Assets
Derivative Asset	98,645
Liabilities
Derivative liabilities	99,012
Interest Rate Contract [Member] \| Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 1
Assets
Derivative Asset	0
Liabilities
Derivative liabilities	0
Interest Rate Contract [Member] \| Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 2
Assets
Derivative Asset	98,645
Liabilities
Derivative liabilities	99,012
Interest Rate Contract [Member] \| Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 3
Assets
Derivative Asset	0
Liabilities
Derivative liabilities	0
Foreign Exchange [Member] \| Fair Value, Measurements, Recurring
Assets
Derivative Asset	49,539
Liabilities
Derivative liabilities	49,539
Foreign Exchange [Member] \| Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 1
Assets
Derivative Asset	0
Liabilities
Derivative liabilities	0
Foreign Exchange [Member] \| Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 2
Assets
Derivative Asset	49,539
Liabilities
Derivative liabilities	49,539
Foreign Exchange [Member] \| Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 3
Assets
Derivative Asset	0
Liabilities
Derivative liabilities	$ 0

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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