Business Combination, Number Of Retirement Plans Assumed

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- Definition

Deferred Compensation Arrangement With Individual, Calculation Of Postretirement Benefits, Number Of Consecutive Years

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No definition available.

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- Definition

Deferred Compensation Arrangement With Individual, Calculation Of Postretirement Benefits, Term

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- Definition

Defined Contribution Plan, Employer Non-Elective Contribution, Vesting Period

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- Definition

Number of Defined Benefit Pension Plans

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No definition available.

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- Definition

Maximum term of the deferred compensation arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Minimum period the individual is required to perform services to be fully vested under the deferred compensation arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Aggregate carrying value as of the balance sheet date of the liabilities for stock option plans and other equity-based compensation arrangements.

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No definition available.

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- Definition

Amount of actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level.

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- Definition

Amount of asset, recognized in statement of financial position, for overfunded defined benefit pension and other postretirement plans.

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- Definition

Weighted-average interest crediting rate used to determine net periodic benefit cost of defined benefit plan. Plan includes, but is not limited to, cash balance and other defined benefit plans with promised interest crediting rate.

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- Definition

Amount of payment, which decreases benefit obligation of defined benefit plan, for irrevocable action relieving primary responsibility for benefit obligation and eliminating risk for obligation and assets used to effect settlement. Transaction constituting settlement includes, but is not limited to, making lump-sum cash payment to participant in exchange for their rights to receive specified benefits and purchasing nonparticipating annuity contract. Excludes decreases to benefit obligation for remeasurement due to settlement.

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Amount of contribution received by defined benefit plan from employer which increases plan assets.

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- Definition

Amount of cost for defined contribution plan.

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Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

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No definition available.

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Percentage employer matches of the employee's percentage contribution matched.

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- Definition

Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Employee Benefit Plans - Narrative (Details)	12 Months Ended
Employee Benefit Plans - Narrative (Details)	Dec. 31, 2023 USD ($) defined_benefit_plan	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jan. 03, 2022 retirement_plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of defined benefit pension plans \| defined_benefit_plan	3
Interest crediting rate	4.25%	1.50%
Pension assets	$ 474,000,000	$ 343,000,000
Defined benefit plan, accumulated benefit obligation	1,120,000,000	1,070,000,000.00
Defined contribution plan, cost	$ 114,000,000	55,000,000	$ 36,000,000
Deferred compensation arrangement with individual, maximum contractual term	10 years
Incentive plan liabilities	$ 676,000,000	267,000,000
Postretirement Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employer contributions	0	0
Number of retirement plans assumed \| retirement_plan				4
Plan termination	0	27,000,000
BancShares Pension Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employer contributions	$ 0	0
Vesting period	5 years
Number of consecutive years	5 years
Calculation of postretirement benefits, term	10 years
Bancorporation Pension Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employer contributions	$ 0	0
Vesting period	5 years
Number of consecutive years	5 years
Calculation of postretirement benefits, term	10 years
CIT Pension Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employer contributions	$ 0	0
Supplemental and Executive Retirement Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employer contributions	$ 0	$ 0
Interest crediting rate	3.90%	1.90%
401(k) Contribution Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of defined benefit pension plans \| defined_benefit_plan	2
FCB Legacy 401(k) Plan \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Defined contribution plan, employer matching contribution, percent of employees' gross pay	4.50%
FCB 401(k) Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Defined contribution plan, employer matching contribution, percent of match	100.00%
Defined contribution plan, employer non-elective contribution, vesting period	3 years
FCB 401(k) Plan \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Defined contribution plan, employer matching contribution, percent of employees' gross pay	6.00%
CIT 401(k) Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Defined contribution plan, employer matching contribution, percent of match	100.00%
CIT 401(k) Plan \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Defined contribution plan, employer matching contribution, percent of employees' gross pay	4.00%
Defined Contribution Plan, Employer Matching Contribution, First Portion \| FCB Legacy 401(k) Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Defined contribution plan, employer matching contribution, percent of match	100.00%
Defined contribution plan, employer matching contribution, percent of employees' gross pay	3.00%
Defined Contribution Plan, Employer Matching Contribution, Next Portion \| FCB Legacy 401(k) Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Defined contribution plan, employer matching contribution, percent of match	50.00%
Defined contribution plan, employer matching contribution, percent of employees' gross pay	3.00%
Defined Contribution Plan, Employer Matching Contribution, Minimum Contribution \| FCB 401(k) Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Defined contribution plan, employer matching contribution, percent of employees' gross pay	3.00%
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs vesting period	3 years
RSUs vested and settled in period, fair value	$ 16,000,000	$ 64,000,000