FAIR VALUE DISCLOSURES - Summary of Financial Assets and Liabilities Measure at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Assets
Investment securities available-for-sale	$ 2,897,413
Derivative Asset	295,424	$ 112,607
Liabilities
Derivative liabilities	295,705	112,616
Fair Value, Measurements, Recurring
Assets
Investment securities available-for-sale	2,897,413	2,852,084
Derivative Asset		73,558
Total	3,192,999	2,964,814
Liabilities
Total	296,618	112,922
Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 1
Assets
Investment securities available-for-sale	104	100
Derivative Asset		0
Total	104	100
Liabilities
Total	0	0
Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 2
Assets
Investment securities available-for-sale	2,855,732	2,842,794
Derivative Asset		73,558
Total	3,151,318	2,955,524
Liabilities
Total	296,618	112,922
Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 3
Assets
Investment securities available-for-sale	41,577	9,190
Derivative Asset		0
Total	41,577	9,190
Liabilities
Total	0	0
Interest Rate Contract [Member] \| Fair Value, Measurements, Recurring
Assets
Derivative Asset	219,291
Liabilities
Derivative liabilities	220,323	73,750
Interest Rate Contract [Member] \| Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 1
Assets
Derivative Asset	0
Liabilities
Derivative liabilities	0	0
Interest Rate Contract [Member] \| Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 2
Assets
Derivative Asset	219,291
Liabilities
Derivative liabilities	220,323	73,750
Interest Rate Contract [Member] \| Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 3
Assets
Derivative Asset	0
Liabilities
Derivative liabilities	0	0
Foreign Exchange [Member] \| Fair Value, Measurements, Recurring
Assets
Derivative Asset	76,295	39,172
Liabilities
Derivative liabilities	76,295	39,172
Foreign Exchange [Member] \| Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 1
Assets
Derivative Asset	0	0
Liabilities
Derivative liabilities	0	0
Foreign Exchange [Member] \| Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 2
Assets
Derivative Asset	76,295	39,172
Liabilities
Derivative liabilities	76,295	39,172
Foreign Exchange [Member] \| Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 3
Assets
Derivative Asset	0	0
Liabilities
Derivative liabilities	$ 0	$ 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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