Securities (Amortized Cost and Fair Value of Debt Securities by Contractual Maturity) (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Debt Securities Available for Sale, Due in one year or less, Amortized Cost	$ 323
Debt Securities Available for Sale, Due after one year through five years, Amortized Cost	825,767
Debt Securities Available for Sale, Due after five years through ten years, Amortized Cost	2,932,193
Debt Securities Available for Sale, Due after ten years, Amortized Cost	2,600,151
Securities Available for Sale, Gross Amortized Cost	6,358,434	$ 6,984,530
Debt Securities Available for Sale, Due in one year or less, Fair Value	326
Debt Securities Available for Sale, Due after one year through five years, Fair Value	803,642
Debt Securities Available for Sale, Due after five years through ten years, Fair Value	2,674,994
Debt Securities Available for Sale, Due after ten years, Fair Value	2,300,419
Total available for sale debt securities, Fair Value	5,779,381	6,986,698
Debt Securities Held to Maturity, Due in one year or less, Amortized Cost	11,035
Debt Securities Held to Maturity, Due after one year through five years, Amortized Cost	385,208
Debt Securities Held to Maturity, Due after five years through ten years, Amortized Cost	951,715
Debt Securities Held to Maturity, Due after ten years, Amortized Cost	1,404,054
Total held to maturity debt securities, Amortized Cost	2,752,012	1,565,751
Debt Securities Held to Maturity, Due in one year or less, Fair Value	11,005
Debt Securities Held to Maturity, Due after one year through five years, Fair Value	380,049
Debt Securities Held to Maturity, Due after five years through ten years, Fair Value	905,108
Debt Securities Held to Maturity, Due after ten years, Fair Value	1,319,636
Total held to maturity debt securities, Fair Value	$ 2,615,798	$ 1,631,482