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FAIR VALUE DISCLOSURES - Summary of Financial Assets and Liabilities Measure at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Assets
Loans Held-for-sale, Fair Value Disclosure	$ 33,800		$ 41,100
Derivative Asset	240,010		272,499
Liabilities
Derivative liabilities	240,086		272,606
Fair Value, Option, Changes in Fair Value, Gain (Loss)	(200)	$ 2,500
Financing Receivable, Held-for-Sale	30,500		35,500
Fair Value, Option, Aggregate Differences, Loans and Long-term Receivables	3,300		5,600
Investment securities available-for-sale, at fair value (amortized cost $4,065,301 at September 30, 2021 and $3,330,029 at December 31, 2020)	4,114,094		3,424,580
Fair Value, Measurements, Recurring
Assets
Derivative Asset			185,032
Total	4,388,027		3,738,330
Liabilities
Total	240,291		273,739
Investment securities available-for-sale, at fair value (amortized cost $4,065,301 at September 30, 2021 and $3,330,029 at December 31, 2020)	4,114,094		3,424,580
Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 1 \| Fair value
Assets
Loans Held-for-sale, Fair Value Disclosure	0		0
Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 1
Assets
Derivative Asset			0
Total	20,330		103
Liabilities
Total	0		0
Investment securities available-for-sale, at fair value (amortized cost $4,065,301 at September 30, 2021 and $3,330,029 at December 31, 2020)	20,330		103
Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 2 \| Fair value
Assets
Loans Held-for-sale, Fair Value Disclosure	33,835		41,103
Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 2
Assets
Derivative Asset			185,032
Total	4,329,331		3,697,652
Liabilities
Total	240,291		273,739
Investment securities available-for-sale, at fair value (amortized cost $4,065,301 at September 30, 2021 and $3,330,029 at December 31, 2020)	4,055,398		3,383,902
Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 3 \| Fair value
Assets
Loans Held-for-sale, Fair Value Disclosure	0		0
Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 3
Assets
Derivative Asset			0
Total	38,366		40,575
Liabilities
Total	0		0
Investment securities available-for-sale, at fair value (amortized cost $4,065,301 at September 30, 2021 and $3,330,029 at December 31, 2020)	38,366		40,575
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 1, 2 and 3
Assets
Loans Held-for-sale, Fair Value Disclosure	33,835		41,103
Interest Rate Contract [Member] \| Fair Value, Measurements, Recurring
Assets
Derivative Asset	113,601
Liabilities
Derivative liabilities	113,794		186,124
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	113,601
Liabilities
Derivative liabilities	113,794		186,124
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 \| Fair Value, Measurements, Recurring
Assets
Derivative Asset	126,497		87,615
Liabilities
Derivative liabilities	126,497		87,615
Foreign Exchange \| Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 1
Assets
Derivative Asset	0		0
Liabilities
Derivative liabilities	0		0
Foreign Exchange \| Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 2
Assets
Derivative Asset	126,497		87,615
Liabilities
Derivative liabilities	126,497		87,615
Foreign Exchange \| Fair Value, Measurements, Recurring \| Fair Value Measurements Using Level 3
Assets
Derivative Asset	0		0
Liabilities
Derivative liabilities	$ 0		$ 0