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The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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Amount of increase in the fair value of derivatives recognized in the income statement.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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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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No definition available.

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Amount of decrease in the fair value of derivatives recognized in the income statement.

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Nominal or face amount used to calculate payment on derivative.

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Fair value as of the balance sheet date of interest rate derivative assets, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as assets.

+ References

No definition available.

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Fair value as of the balance sheet date of interest rate derivative liabilities, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as liabilities.

+ References

No definition available.

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Fair value as of the balance sheet date of interest rate derivative assets, net of interest rate derivative liabilities, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized on the balance sheet.

+ References

No definition available.

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Fair value of financial and nonfinancial obligations.

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The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of open derivatives, commodity, or energy contracts, held at each balance sheet date, that was included in earnings for the period.

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Derivative Financial Instruments (Details) - USD ($)	3 Months Ended		12 Months Ended
Derivative Financial Instruments (Details) - USD ($)	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Derivative Financial Instruments
Notional Amount	$ 20,157,553,000		$ 19,342,657,000
Estimated Fair Value Gain	416,329,000		813,899,000
Estimated Fair Value Loss	402,256,000		804,832,000
Interest Rate Derivative Assets, at Fair Value	398,200,000		802,800,000
Interest Rate Derivative Liabilities, at Fair Value	398,200,000		802,700,000
Interest Rate Derivatives, at Fair Value, Net	14,000		17,000
Obligation under forward commitments, the fair value of those obligations along with the fair value of derivative instruments associated with forward commitments
Fair value of forward commitments	(402,256,000)		(804,832,000)
Mortgage loan pipeline
Obligation under forward commitments, the fair value of those obligations along with the fair value of derivative instruments associated with forward commitments
Obligation	634,976,000		510,730,000
Expected closures
Obligation under forward commitments, the fair value of those obligations along with the fair value of derivative instruments associated with forward commitments
Obligation	562,805,000		411,273,000
Cash flow hedge \| Borrower
Derivative Financial Instruments
Collateral provided	366,800,000
Interest rate contracts
Derivative Financial Instruments
Notional Amount	19,400,000,000		18,600,000,000
Mortgage servicing rights hedging \| Non-designated hedges
Derivative Financial Instruments
Notional Amount	152,000,000.0		149,000,000.0
Estimated gain (loss) on fair value	(2,600,000)	$ 1,100,000	119,000
Mortgage servicing rights hedging \| Non-designated hedges \| Other Liabilities
Derivative Financial Instruments
Notional Amount	152,000,000		149,000,000
Estimated Fair Value Gain			119,000
Estimated Fair Value Loss	2,631,000
Mortgage loan pipeline commitments hedging
Obligation under forward commitments, the fair value of those obligations along with the fair value of derivative instruments associated with forward commitments
Obligation	10,524,000		15,328,000
Mortgage loan pipeline commitments hedging \| Non-designated hedges \| Other Assets
Derivative Financial Instruments
Notional Amount	593,500,000		528,500,000
Estimated Fair Value Gain	18,108,000		11,017,000
Forward commitments
Obligation under forward commitments, the fair value of those obligations along with the fair value of derivative instruments associated with forward commitments
Obligation	593,500,000		528,500,000
Fair value of forward commitments	7,584,000
Fair value of forward commitments			(4,311,000)
Customer swaps \| Cash flow hedge \| Investment securities - available for sale
Derivative Financial Instruments
Collateral provided	558,000,000.0
Foreign exchange swaps
Derivative Financial Instruments
Gain or loss recorded	0	0
Interest rate swap \| Fair Value Hedging \| Counterparty
Derivative Financial Instruments
Notional Amount	16,300,000		16,400,000
Gain or loss recorded	0	$ 0
Interest rate swap \| Fair Value Hedging \| Other Liabilities \| Counterparty
Derivative Financial Instruments
Notional Amount	16,307,000		16,439,000
Estimated Fair Value Loss	1,390,000		2,086,000
Interest rate swap \| Non-designated hedges \| Other Assets and Other Liabilities \| Borrower
Derivative Financial Instruments
Notional Amount	9,697,873,000		9,324,359,000
Estimated Fair Value Gain	393,424,000		802,717,000
Estimated Fair Value Loss	120,458,000		46,000
Interest rate swap \| Non-designated hedges \| Other Assets and Other Liabilities \| Counterparty
Derivative Financial Instruments
Notional Amount	9,697,873,000		9,324,359,000
Estimated Fair Value Gain	4,797,000		46,000
Estimated Fair Value Loss	$ 277,777,000		$ 802,700,000