Investment Securities (Narrative) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	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	$ 1,600,000		$ 1,300,000
Debt Securities, Available-for-sale, Unrealized Loss Position	10,370,998		12,027,745
Unrealized Loss on AFS Debt Securities	1,419,393		1,500,632
AFS securities in loss position at period-end, change in unrealized loss	(81,200)
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	$ 206,400
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	395,400
Debt Securities, Available-for-sale, Unrealized Loss Position	945,815		986,413
Unrealized Loss on AFS Debt Securities	39,169		$ 43,430
Available-for-sale Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Realized Gain (Loss)	(8,400)
Equity Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Equity Securities, FV-NI, Unrealized Gain (Loss)	(690)	$ (1,023)
Other Investments [Member]
Debt Securities, Available-for-sale [Line Items]
Other Securities, Gains realized on sales	879	27
Fair value other securities adjustments, net	$ 11,341	$ 23,083