Fair Value Accounting (Tables)

12 Months Ended

Dec. 31, 2021

Fair Value Disclosures [Abstract]

Gains and Losses from Fair Value Changes Included in Consolidated Statement of Operations

For the years ended December 31, 2021, 2020, and 2019, unrealized losses from fair value changes on junior subordinated debt were as follows:

	Year Ended December 31,
	2021		2020		2019
	(in millions)
Unrealized losses	$	(1.5)	$	(4.2)	$	(13.0)
Changes included in OCI, net of tax	(1.2)		(3.1)		(9.8)

Fair Value of Assets and Liabilities

The fair value of assets and liabilities measured at fair value on a recurring basis was determined using the following inputs as of the periods presented: 

	Fair Value Measurements at the End of the Reporting Period Using:
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Fair Value
	(in millions)
December 31, 2021
Available-for-sale debt securities
CLO	$	—	$	926.2	$	—	$	926.2
Commercial MBS issued by GSEs	—		68.5		—		68.5
Corporate debt securities	—		382.9		—		382.9
Private label residential MBS	—		1,508.0		—		1,508.0
Residential MBS issued by GSEs	—		1,993.4		—		1,993.4
Tax-exempt	—		1,215.1		—		1,215.1
U.S. treasury securities	13.0		—		—		13.0
Other	27.4		54.3		—		81.7
Total AFS debt securities	$	40.4	$	6,148.4	$	—	$	6,188.8
Equity securities
CRA investments	$	27.4	$	17.2	$	—	$	44.6
Preferred stock	113.9		—		—		113.9
Total equity securities	$	141.3	$	17.2	$	—	$	158.5
Loans HFS	$	—	$	3,894.2	$	45.5	$	3,939.7
Mortgage servicing rights	—		—		698.0		698.0
Derivative assets (1)	—		39.2		11.0		50.2
Liabilities:
Junior subordinated debt (2)	$	—	$	—	$	67.4	$	67.4
Derivative liabilities (1)	—		98.2		1.6		99.8

(1)See "Note 15. Derivatives and Hedging Activities." In addition, the carrying value of loans is increased by $38.5 million as of December 31, 2021 for the effective portion of the hedge, which relates to the fair value of the hedges put in place to mitigate against fluctuations in interest rates.

(2)Includes only the portion of junior subordinated debt that is recorded at fair value at each reporting period pursuant to the election of FVO treatment.

	Fair Value Measurements at the End of the Reporting Period Using:
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Fair Value
	(in millions)
December 31, 2020
Assets:
Available-for-sale debt securities
CLO	$	—	$	146.9	$	—	$	146.9
Commercial MBS issued by GSEs	—		84.6		—		84.6
Corporate debt securities	—		270.2		—		270.2
Private label residential MBS	—		1,476.9		—		1,476.9
Residential MBS issued by GSEs	—		1,486.6		—		1,486.6
Tax-exempt	—		1,187.4		—		1,187.4
Other	26.5		29.4		—		55.9
Total AFS debt securities	$	26.5	$	4,682.0	$	—	$	4,708.5
Equity securities
CRA investments	$	27.8	$	25.6	$	—	$	53.4
Preferred stock	113.9		—		—		113.9
Total equity securities	$	141.7	$	25.6	$	—	$	167.3
Derivative assets (1)	$	—	$	4.2	$	—	$	4.2
Liabilities:
Junior subordinated debt (2)	$	—	$	—	$	65.9	$	65.9
Derivative liabilities (1)	—		87.5		—		87.5

(1)See "Note 15. Derivatives and Hedging Activities." In addition, the carrying value of loans is increased by $85.5 million and the net carrying value of subordinated debt is decreased by $2.7 million as of December 31, 2020, which relates to the effective portion of the hedges put in place to mitigate against fluctuations in interest rates.

Change in Level 3 Liabilities Measured at Fair Value on Recurring Basis

For the years ended December 31, 2021, 2020, and 2019, the change in Level 3 liabilities measured at fair value on a recurring basis included in OCI was as follows: 

	Junior Subordinated Debt
	Year Ended December 31,
	2021		2020		2019
	(in millions)
Beginning balance	$	(65.9)	$	(61.7)	$	(48.7)
Change in fair value (1)	(1.5)		(4.2)		(13.0)
Ending balance	$	(67.4)	$	(65.9)	$	(61.7)

(1)Unrealized gains/(losses) attributable to changes in the fair value of junior subordinated debt are recorded as part of OCI, net of tax, and totaled $(1.2) million, $(3.1) million, and $(9.8) million for the years ended December 31, 2021, 2020, and 2019, respectively.

The significant unobservable inputs used in the fair value measurements of these Level 3 liabilities were as follows: 

	December 31, 2021		Valuation Technique	Significant Unobservable Inputs	Input Value
	(in millions)
Junior subordinated debt	$	67.4	Discounted cash flow	Implied credit rating of the Company	2.61	%

Assets Measured at Fair Value on Nonrecurring Basis

The following table presents such assets carried on the Consolidated Balance Sheet by caption and by level within the ASC 825 hierarchy:

	Fair Value Measurements at the End of the Reporting Period Using
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Active Markets for Similar Assets (Level 2)		Unobservable Inputs (Level 3)
	(in millions)
As of December 31, 2021
Loans HFI	$	216.0	$	—	$	—	$	216.0
Other assets acquired through foreclosure	11.7		—		—		11.7
As of December 31, 2020
Loans HFI	$	187.3	$	—	$	—	$	187.3
Other assets acquired through foreclosure	1.4		—		—		1.4

Estimated Fair Value of Financial Instruments

The estimated fair value of the Company’s financial instruments is as follows: 

	December 31, 2021
	Carrying Amount		Fair Value
			Level 1		Level 2		Level 3		Total
	(in millions)
Financial assets:
Investment securities:
HTM	$	1,107.1	$	—	$	1,146.4	$	—	$	1,146.4
AFS	6,188.8		40.4		6,148.4		—		6,188.8
Equity securities	158.5		141.3		17.2		—		158.5
Derivative assets	50.2		—		39.2		11.0		50.2
Loans HFS	5,635.1		—		3,894.2		1,760.2		5,654.4
Loans HFI, net	38,822.9		—		—		39,218.2		39,218.2
Mortgage servicing rights	698.0		—		—		698.0		698.0
Accrued interest receivable	227.9		—		227.9		—		227.9
Financial liabilities:
Deposits	$	47,612.0	$	—	$	47,615.5	$	—	$	47,615.5
Other borrowings	1,501.9		—		1,518.4		—		1,518.4
Qualifying debt	895.8		—		857.3		81.3		938.6
Derivative liabilities	99.8		—		98.2		1.6		99.8
Accrued interest payable	9.2		—		9.2		—		9.2