Securities Securities - Amortized Cost, Allowance for Credit Losses and Estimated Fair Value of Securities Held to Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Schedule of Investments [Line Items]
Held to Maturity, Amortized Cost	$ 2,174,242	$ 1,749,337
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	90	59,907
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	257,045	101
Debt Securities, Held-to-maturity, Fair Value	1,917,287	1,809,143
Securities, held-to-maturity, allowance for credit loss	(158)	(158)
Securities held to maturity, net of allowance for credit losses of $158 at September 30, 2022 and $158 at December 31, 2021	2,174,084	1,749,179
Residential Mortgage Backed Securities [Member]
Schedule of Investments [Line Items]
Held to Maturity, Amortized Cost	526,397	527,264
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	18,766
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	68,024	0
Debt Securities, Held-to-maturity, Fair Value	458,373	546,030
Securities, held-to-maturity, allowance for credit loss	0	0
Securities held to maturity, net of allowance for credit losses of $158 at September 30, 2022 and $158 at December 31, 2021	526,397	527,264
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Held to Maturity, Amortized Cost	1,646,345	1,220,573
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	90	41,141
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	188,964	101
Debt Securities, Held-to-maturity, Fair Value	1,457,471	1,261,613
Securities, held-to-maturity, allowance for credit loss	(158)	(158)
Securities held to maturity, net of allowance for credit losses of $158 at September 30, 2022 and $158 at December 31, 2021	1,646,187	1,220,415
Other Investments [Member]
Schedule of Investments [Line Items]
Held to Maturity, Amortized Cost	1,500	1,500
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	57	0
Debt Securities, Held-to-maturity, Fair Value	1,443	1,500
Securities, held-to-maturity, allowance for credit loss	0	0
Securities held to maturity, net of allowance for credit losses of $158 at September 30, 2022 and $158 at December 31, 2021	$ 1,500	$ 1,500