Securities (Amortized Cost and Fair Value of Debt Securities by Contractual Maturity) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Investments, Debt and Equity Securities [Abstract]
Debt Securities Available for Sale, Due in one year or less, Amortized cost	$ 115,178
Debt Securities Available for Sale, Due after one year through five years, Amortized cost	439,302
Debt Securities Available for Sale, Due after five years through ten years, Amortized cost	2,638,039
Debt Securities Available for Sale, Due after ten years, Amortized cost	2,304,199
Securities Available for Sale, Gross Amortized cost	5,496,718	$ 6,310,214
Debt Securities Available for Sale, Due in one year or less, Fair value	113,610
Debt Securities Available for Sale, Due after one year through five years, Fair value	429,623
Debt Securities Available for Sale, Due after five years through ten years, Fair value	2,385,895
Debt Securities Available for Sale, Due after ten years, Fair value	1,986,067
Total available for sale debt securities, Fair value	4,915,195	5,556,041
Debt Securities Held to Maturity, Due in one year or less, Amortized cost	91,699
Debt Securities Held to Maturity, Due after one year through five years, Amortized cost	664,913
Debt Securities Held to Maturity, Due after five years through ten years, Amortized cost	791,158
Debt Securities Held to Maturity, Due after ten years, Amortized cost	1,137,009
Total held to maturity debt securities, Amortized cost	2,684,779	2,852,495
Debt Securities Held to Maturity, Due in one year or less, Fair value	90,110
Debt Securities Held to Maturity, Due after one year through five years, Fair value	634,463
Debt Securities Held to Maturity, Due after five years through ten years, Fair value	742,927
Debt Securities Held to Maturity, Due after ten years, Fair value	1,018,418
Total held to maturity debt securities, Fair value	$ 2,485,918	$ 2,615,398