Investment Securities Schedule of Amortized Cost and Fair Values of Debt Securities by Contractual Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Available for Sale
Due in one year or less	$ 9,053
Due from one year to five years	163,249
Due from five years to ten years	391,040
Due after ten years	1,153,508
Amortized cost, before securities without debt maturities	1,716,850
Amortized Cost	3,129,530	$ 2,947,500
Estimated Fair Value
Due in one year or less	9,175
Due from one year to five years	163,924
Due from five years to ten years	405,782
Due after ten years	1,198,207
Available for sale securities, debt maturities, before securities without single maturities	1,777,088
Estimated Fair Value	3,187,390	3,062,143
Amortized Cost
Due in one year or less	0
Due from one year to five years	0
Due from five years to ten years	0
Due after ten years	0
Debt securities, held-to-maturity, maturity, allocated and single maturity date, amortized cost, total	0
Amortized Cost	980,384	278,281
Estimated Fair Value
Due in one year or less	0
Due from one year to five years	0
Due from five years to ten years	0
Due after ten years	0
Debt securities, held-to-maturity, maturity, Allocated and single maturity date, fair value	0
Total	965,867
Residential mortgage-backed securities
Available for Sale
Available-for-sale securities, amortized cost without single maturity date	231,607
Amortized Cost	231,607	373,779
Estimated Fair Value
Available-for-sale securities, debt maturities, without single maturity date, fair value	229,795
Estimated Fair Value	229,795	377,998
Amortized Cost
Debt securities, held-to-maturity, maturity, without single maturity date, amortized cost	404,958
Amortized Cost	404,958	278,281
Estimated Fair Value
Debt securities, held-to-maturity, maturity, without single maturity date, fair value	408,913
Total	408,913	296,857
Commercial mortgage-backed securities
Available for Sale
Available-for-sale securities, amortized cost without single maturity date	974,541
Amortized Cost	974,541	741,172
Estimated Fair Value
Available-for-sale securities, debt maturities, without single maturity date, fair value	971,148
Estimated Fair Value	971,148	762,415
Amortized Cost
Debt securities, held-to-maturity, maturity, without single maturity date, amortized cost	575,426
Amortized Cost	575,426
Estimated Fair Value
Debt securities, held-to-maturity, maturity, without single maturity date, fair value	556,954
Total	556,954
Collateralized mortgage obligations
Available for Sale
Available-for-sale securities, amortized cost without single maturity date	206,532
Amortized Cost	206,532	491,321
Estimated Fair Value
Available-for-sale securities, debt maturities, without single maturity date, fair value	209,359
Estimated Fair Value	209,359	$ 503,766
Amortized Cost
Debt securities, held-to-maturity, maturity, without single maturity date, amortized cost	0
Estimated Fair Value
Debt securities, held-to-maturity, maturity, without single maturity date, fair value	$ 0