Securities (Amortized Cost and Fair Value of Debt Securities by Contractual Maturity) (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Debt Securities Available for Sale, Due in one year or less, Amortized Cost	$ 101
Debt Securities Available for Sale, Due after one year through five years, Amortized Cost	848,598
Debt Securities Available for Sale, Due after five years through ten years, Amortized Cost	2,973,944
Debt Securities Available for Sale, Due after ten years, Amortized Cost	2,519,736
Securities Available for Sale, Gross Amortized Cost	6,342,379	$ 6,984,530
Debt Securities Available for Sale, Due in one year or less, Fair Value	101
Debt Securities Available for Sale, Due after one year through five years, Fair Value	797,561
Debt Securities Available for Sale, Due after five years through ten years, Fair Value	2,578,481
Debt Securities Available for Sale, Due after ten years, Fair Value	2,090,700
Total available for sale debt securities, Fair Value	5,466,843	6,986,698
Debt Securities Held to Maturity, Due in one year or less, Amortized Cost	10,000
Debt Securities Held to Maturity, Due after one year through five years, Amortized Cost	542,464
Debt Securities Held to Maturity, Due after five years through ten years, Amortized Cost	865,852
Debt Securities Held to Maturity, Due after ten years, Amortized Cost	1,448,032
Total held to maturity debt securities, Amortized Cost	2,866,348	1,565,751
Debt Securities Held to Maturity, Due in one year or less, Fair Value	9,890
Debt Securities Held to Maturity, Due after one year through five years, Fair Value	516,989
Debt Securities Held to Maturity, Due after five years through ten years, Fair Value	782,394
Debt Securities Held to Maturity, Due after ten years, Fair Value	1,296,807
Total held to maturity debt securities, Fair Value	$ 2,606,080	$ 1,631,482