RECENTLY ADOPTED AND ISSUED ACCOUNTING STANDARDS - Additional Information (Details) - USD ($) $ in Thousands		9 Months Ended
	Jan. 01, 2020	Sep. 30, 2020		Jun. 30, 2020	Dec. 31, 2019		Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Losses, Effect of Change in Method	$ 61,505	$ 61,505
Off-Balance Sheet, Credit Loss, Liability, Change in Method, Credit Loss Expense (Reversal)	12,155
Deferred tax liability, Credit Loss, Change in Method, Credit Loss Expense (Reversal)	(16,778)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest				$ 2,221,019	$ 2,247,705			$ 2,188,189	$ 2,078,249
Loans and Leases Receivable, Allowance	$ 119,155	$ 168,544	[1]	158,661	57,650	[1]	$ 56,552	61,549	56,542
Cumulative Effect, Period of Adoption, Adjustment [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest					(56,882)				3,542
Retained earnings
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest				$ 675,532	711,249		$ 685,368	$ 657,730	600,014
Retained earnings | Cumulative Effect, Period of Adoption, Adjustment [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest					$ (56,882)				$ 2,636

[1] Beginning January 1, 2020, calculation is based on current expected loss methodology. Prior to January 1, 2020, calculation was based on incurred loss methodology.