Investment Securities (Narrative) (Details)	12 Months Ended
	Dec. 31, 2023 USD ($) shares	Jan. 24, 2024 shares	Dec. 31, 2022 USD ($)
Investment [Line Items]
Interest Receivable	$ 71,900,000		$ 55,500,000
Equity Securities without Readily Determinable Fair Value, Amount	$ 6,978,000		6,094,000
Percentage decrease requiring a review for impairment	20.00%
Fair value of securities on other-than-temporary impairment watch list	$ 1,200,000,000		1,300,000,000
Debt Securities, Available-for-sale, Unrealized Loss Position	9,593,950,000		12,027,745,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	1,220,484,000		1,500,632,000
Available for sale securities in loss position at period end, change in unrealized loss	(280,100,000)
Securities pledged as collateral	$ 7,500,000,000		4,700,000,000
Number of investments in a single issuer that exceed 10% of stockholder's equity	0
No investment in a single issuer exceeds this percentage of stockholder's equity	10.00%
Asset Pledged as Collateral with Right
Investment [Line Items]
Financial Instruments, Owned, at Fair Value	$ 208,000
Visa Class B Shares [Member]
Investment [Line Items]
Equity Securities without Readily Determinable Fair Value, Shares | shares	823,447
Equity Securities without Readily Determinable Fair Value, Amount	$ 0
Visa Class B-1 Shares | Subsequent Event [Member]
Investment [Line Items]
Equity Securities without Readily Determinable Fair Value, Share Class Redenomination | shares		823,447
US Treasury and Government [Member]
Investment [Line Items]
U.S. Treasury inflation-protected securities held	404,400,000
Debt Securities, Available-for-sale, Unrealized Loss Position	765,985,000		986,413,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	24,834,000		43,430,000
Investment Securities
Investment [Line Items]
Interest Receivable	$ 28,900,000		$ 38,800,000