Short-Term Borrowings (Narrative) (Details) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023 USD ($) Item	Dec. 31, 2022 USD ($) Item
Short-Term Debt [Line Items]
Short-term borrowings	$ 1,425,928	$ 1,871,271
FHLB Borrowings [Member]
Short-Term Debt [Line Items]
Short-term borrowings	$ 900,000	$ 1,425,000
FHLB Borrowings [Member] | FHLB Borrowings, Redemption Period One [Member] | Fixed-rate Whole Loan Advances and Term Notes [Member]
Short-Term Debt [Line Items]
Number of fixed rate short-term borrowings | Item	2	1
Short-term maturity year	2023	2023