Investment Securities (Narrative) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2023 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2022 USD ($)
Debt Securities, Available-for-sale [Line Items]
Percentage decrease requiring a review for impairment	20.00%
Fair value of securities on impairment watch list	$ 676,000		$ 1,300,000
Debt Securities, Available-for-sale, Unrealized Loss Position	11,034,069		12,027,745
Unrealized Loss on AFS Debt Securities	1,311,915		1,500,632
AFS securities in loss position at period-end, change in unrealized loss	(188,700)
Securities pledged as collateral	$ 8,100,000		4,700,000
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
Debt Securities, Available-for-sale [Line Items]
Securities pledged as collateral, amount eligible to be repledged by Counterparty	$ 211,500
Visa Class B Shares
Debt Securities, Available-for-sale [Line Items]
Equity Securities without Readily Determinable Fair Value, Amount	0
U.S. government and federal agency obligations
Debt Securities, Available-for-sale [Line Items]
U.S. Treasury inflation-protected securities held, at fair value	402,300
Debt Securities, Available-for-sale, Unrealized Loss Position	918,982		986,413
Unrealized Loss on AFS Debt Securities	30,009		$ 43,430
Available-for-sale Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Losses realized on sales	(3,088)	$ 0
Equity Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Equity Securities, FV-NI, Unrealized Gain (Loss)	(127)	(287)
Other Investments [Member]
Debt Securities, Available-for-sale [Line Items]
Other Securities, Gains realized on sales	658	0
Fair value other securities adjustments, net	$ 2,251	$ 7,450