DERIVATIVES (Gains (Losses) on All Derivatives) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Pay fixed-receive variable interest rate swaps | Interest expense on borrowings | Cash flow hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized on derivatives	$ (8,939)	$ 8,283	$ (17,260)	$ 35,065
Pay variable receive-fixed interest rate swap | Interest income on loans | Cash flow hedges
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized on derivatives	34,767	(11,324)	57,691	(34,022)
Forward commitments to sell loans | Miscellaneous income, net
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized on derivatives	3,175	5,349	85	6,183
Interest rate lock commitments | Miscellaneous income, net
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized on derivatives	(316)	(373)	13,077	1,421
Mortgage servicing | Miscellaneous income, net
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized on derivatives	62	9,886	32,175	31,187
Customer-related derivatives | Miscellaneous income, net
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized on derivatives	5,741	10,559	13,861	(5,791)
Foreign exchange | Miscellaneous income, net
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized on derivatives	755	(4,518)	13,560	25,459
Interest rate swaps, caps, and options | Miscellaneous income, net
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized on derivatives	(567)	2,479	(11,253)	10,345
Other | Miscellaneous income, net
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized on derivatives	$ 4,502	$ 453	$ 583	$ 85