NEW ACCOUNTING STANDARDS (Details) - USD ($) $ in Millions		6 Months Ended
	Jan. 01, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit loss	$ 196.0	$ 365.0	$ 343.0	$ 196.0	$ 188.0	$ 186.0	$ 180.0
Financing receivable, allowance for credit loss, period increase (decrease)	105.3	169.1
Stockholders' equity attributable to parent		4,897.0	4,842.0	4,883.0	4,753.0	4,680.0	4,608.0
Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit loss	301.0
Retained Earnings [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' equity attributable to parent		$ 796.0	$ 754.0	$ 798.0	683.0	629.0	576.0
Retained Earnings [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' equity attributable to parent	(51.0)
Originated Loans And Leases [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit loss					$ 183.0	$ 177.0	$ 173.0
Originated Loans And Leases [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Financing receivable, allowance for credit loss, period increase (decrease)	55.0
Longer Duration Loans and Gross Up [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Financing receivable, allowance for credit loss, period increase (decrease)	50.0
Unfunded Loan Commitment [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit loss	10.0
Financing receivable, allowance for credit loss, period increase (decrease)	$ 10.0