CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities:
Net Income (Loss) Attributable to Parent	$ 899.2	$ 506.6	$ 499.2
Adjustments to reconcile net income to cash (used in) provided by operating activities:
(Recovery of) provision for credit losses	(21.4)	(123.6)	(19.3)
Depreciation and amortization	33.7	22.9	18.5
Stock-based compensation	35.1	28.7	26.2
Deferred income taxes	42.0	(25.1)	(5.1)
Amortization of net premiums for investment securities	39.8	28.2	17.1
Amortization of tax credit investments	49.5	49.2	41.5
Amortization of operating lease right of use asset	16.3	11.7	10.5
Amortization of Deferred Loan Origination Fees, Net	(66.3)	(51.2)	(42.7)
Net (gains) losses on:
Fair value (loss) gain on assets measured at fair value, net	(1.3)	3.8	5.1
Changes in other assets and liabilities, net	(157.6)	(15.0)	138.4
Changes in other assets and liabilities, net
Net cash provided by operating activities	(2,654.0)	670.2	717.8
Investment securities - AFS
Purchases	(3,248.4)	(2,966.2)	(927.6)
Principal pay downs and maturities	1,634.1	1,515.5	785.7
Proceeds from sales	164.5	156.6	150.4
Purchases	(595.6)	(182.7)	(131.4)
Principal pay downs and maturities	54.9	17.4	21.6
Proceeds from sales	0.0	0.0	10.0
Purchases	(36.2)	(34.5)	(32.7)
Redemption of principal (reinvestment of dividends)	21.0	7.6	14.6
Proceeds from sales	4.4	0.0	0.0
Proceeds from bank owned life insurance, net	0.0	5.9	0.0
Net increase in loans HFI	(12,665.0)	(5,897.2)	(3,429.0)
Purchase of premises, equipment, and other assets, net	(69.4)	(26.8)	(33.8)
Net cash used in investing activities	(14,711.9)	(7,537.5)	(3,723.0)
Cash flows from financing activities:
Net increase in deposits	15,681.5	9,134.0	3,619.0
Net proceeds from issuance of long-term debt	1,055.7	221.9	0.0
Payments on long-term debt	(475.9)	(75.0)	0.0
Net (decrease) increase in short-term borrowings	(1,742.1)	4.3	(496.7)
Payment, Tax Withholding, Share-based Payment Arrangement	15.8	7.9	9.6
Common stock repurchases	0.0	71.6	120.2
Payments of Dividends	127.6	101.3	51.3
Net cash provided by financing activities	15,210.6	9,104.4	2,941.2
Net (decrease) increase in cash, cash equivalents, and restricted cash	(2,155.3)	2,237.1	(64.0)
Cash, cash equivalents, and restricted cash at beginning of period	2,671.7	434.6	498.6
Cash, cash equivalents, and restricted cash at end of period	516.4	2,671.7	434.6
Cash paid during the period for:
Interest	111.6	108.6	180.4
Income taxes, net	175.7	44.2	(23.4)
Other Significant Noncash Transaction, Description	294.1	(102.2)	36.6
Transfers of securitized LHFS to AFS securities	144.5	0.0	0.0
Payments for Origination and Purchases of Loans Held-for-sale	(59,569.6)	0.0	0.0
Proceeds from Sale and Collection of Loans Held-for-sale	56,647.7	0.0	0.0
Servicing Asset at Fair Value, Additions	(763.8)	0.0	0.0
Other operating activities, net	(16.3)	(9.4)	(5.1)
Servicing Asset at Fair Value, Period Increase (Decrease)	177.7	0.0	0.0
Proceeds from Sale of Mortgage Servicing Rights (MSR)	1,182.8	0.0	0.0
Purchase of other investments	(134.6)	(133.1)	(150.8)
Payments to Acquire Businesses, Net of Cash Acquired	(1,024.4)	0.0	0.0
Proceeds from issuance of common stock in offerings, net	540.3	0.0	0.0
Preferred Stock [Member]
Cash paid during the period for:
Proceeds from Issuance of Preferred Stock and Preference Stock	$ 294.5	$ 0.0	$ 0.0