Available-for-Sale and Held-to-Maturity Securities (Narrative) (Details)	3 Months Ended
Mar. 31, 2023 USD ($) Security	Mar. 31, 2022 USD ($)	Dec. 31, 2022 USD ($)
Other Than Temporary Impairment Credit Losses Recognized In Earnings [Line Items]
Accrued interest receivable	$ 82,600,000		$ 65,700,000
Proceeds from sale of available-for-sale securities	10,000,000.0
Net realized gains (loss) resulting from sale of available-for-sale securities	7,600,000	$ 0
Financial instruments pledged as collateral	$ 796,600,000		796,200,000
Number of available for sale securities whose amortized costs exceeded their fair values \| Security	273
Available-for-sale Securities, Continuous	$ 196,861,000
Available-for-sale Securities, Continuous Unrealized	188,738,000
Available-for-sale Securities, Continuous	$ 1,580,709,000
Percentage of available-for-sale portfolio	97.30%
Pledged [Member]
Other Than Temporary Impairment Credit Losses Recognized In Earnings [Line Items]
Trading securities pledged	$ 1,300,000,000		1,300,000,000
Other Assets [Member]
Other Than Temporary Impairment Credit Losses Recognized In Earnings [Line Items]
Accrued interest receivable	$ 84,600,000		$ 82,300,000

Available for sale securities in unrealized loss positions, percentage of available for sale portfolio.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

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Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position without allowance for credit loss.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of restricted investment in debt security measured at fair value with change in fair value recognized in net income (trading).

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The aggregate fair value as of the balance sheet date of financial instruments and other positions owned by the entity including: (1) mortgages, mortgage-backed and asset backed securities; (2) US government and agency obligations; (3) state and municipal government obligations; (4) other sovereign government debt; (5) corporate obligations; (6) corporate equities; (7) principal investments; (8) derivative contracts; and (9) physical commodities. Includes both pledged and unpledged holdings.

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Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable.

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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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Amount of cash inflow from sale of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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