FAIR VALUE DISCLOSURES - Summary of Financial Assets and Liabilities Measure at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Assets
Investment securities available-for-sale	$ 3,004,963
Derivative Asset	280,730	$ 112,607
Liabilities
Derivative liabilities	280,837	112,616
Fair Value, Measurements, Recurring
Assets
Investment securities available-for-sale	3,004,963	2,852,084
Derivative Asset		73,558
Total	3,285,839	2,964,814
Liabilities
Total	281,834	112,922
Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 1
Assets
Investment securities available-for-sale	103	100
Derivative Asset		0
Total	103	100
Liabilities
Total	0	0
Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 2
Assets
Investment securities available-for-sale	2,964,105	2,842,794
Derivative Asset		73,558
Total	3,244,981	2,955,524
Liabilities
Total	281,834	112,922
Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 3
Assets
Investment securities available-for-sale	40,755	9,190
Derivative Asset		0
Total	40,755	9,190
Liabilities
Total	0	0
Interest Rate Contract [Member] \| Fair Value, Measurements, Recurring
Assets
Derivative Asset	208,443
Liabilities
Derivative liabilities	209,401	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	208,443
Liabilities
Derivative liabilities	209,401	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	72,433	39,172
Liabilities
Derivative liabilities	72,433	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	72,433	39,172
Liabilities
Derivative liabilities	72,433	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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