Investment Securities - Analysis of the Contractual Maturities of Investment Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis Rolling Maturity[Abstract]
Due in One Year or Less	$ 694
Due After One Year Through Five Years	279,784
Due After Five Years Through Ten Years	372,250
Due After Ten Years	13,130
Amortized Cost, Total	665,858
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Rolling Maturities [Abstract]
Available-for-Sale: Amortized Cost	4,548,509	$ 4,320,884
Due in One Year or Less	696
Due After One Year Through Five Years	271,681
Due After Five Years Through Ten Years	345,146
Due After Ten Years	12,012
Fair Value, Total	629,535
Available-for-Sale: Fair Value	4,258,534	4,276,056
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis, Rolling Maturities (Abstract]
Due After One Year Through Five Years	15,781
Due After Five Year Through Ten Years	124,026
Due After Ten Years	11,215
Amortized Cost, Total	151,022
Held-to-Maturity Securities, Debt Maturities, Single Maturity Date, Fair Value, Rolling Maturities [Abstract]
Due After One Year Through Five Years	15,127
Due After Five Year Through Ten Years	115,993
Due After Ten Years	10,143
Fair Value, Total	141,263
Held-to-Maturity: Amortized Cost	4,489,615
Held-to-Maturity: Fair Value	4,171,262	4,646,619
Debt Securities Issued by Government Agencies
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Rolling Maturities [Abstract]
Available-for-sale Securities: Amortized Cost	125,370
Available-for-sale Securities, Debt Securities Issued by Government Agencies and Mortgage-Backed Securities: Fair Value	126,603
Held-to-Maturity Securities, Debt Maturities, Single Maturity Date, Fair Value, Rolling Maturities [Abstract]
Available-for-sale Securities, Debt Securities Issued by Government Agencies and Mortgage-Backed Securities: Fair Value	126,603
Residential - Government Agencies
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Rolling Maturities [Abstract]
Available-for-sale Securities: Amortized Cost	1,368,122
Available-for-Sale: Amortized Cost	1,368,122	1,327,990
Available-for-sale Securities, Debt Securities Issued by Government Agencies and Mortgage-Backed Securities: Fair Value	1,291,150
Available-for-Sale: Fair Value	1,291,150	1,319,042
Held-to-Maturity Securities, Debt Maturities, Single Maturity Date, Fair Value, Rolling Maturities [Abstract]
Held-to-Maturity: Mortgage-Backed Securities: Amortized Cost	1,681,326
Held-to-Maturity: Mortgage-Backed Securities: Amortized Cost	1,681,326
Available-for-sale Securities, Debt Securities Issued by Government Agencies and Mortgage-Backed Securities: Fair Value	1,291,150
Held-to-Maturity: Mortgage-Backed Securities: Fair Value	1,565,974
Held-to-Maturity: Fair Value	1,565,974	1,755,912
Residential - U.S. Government-Sponsored Enterprises
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Rolling Maturities [Abstract]
Available-for-sale Securities: Amortized Cost	2,201,086
Available-for-Sale: Amortized Cost	2,201,086	2,127,781
Available-for-sale Securities, Debt Securities Issued by Government Agencies and Mortgage-Backed Securities: Fair Value	2,030,281
Available-for-Sale: Fair Value	2,030,281	2,090,326
Held-to-Maturity Securities, Debt Maturities, Single Maturity Date, Fair Value, Rolling Maturities [Abstract]
Held-to-Maturity: Mortgage-Backed Securities: Amortized Cost	2,189,122
Held-to-Maturity: Mortgage-Backed Securities: Amortized Cost	2,189,122
Available-for-sale Securities, Debt Securities Issued by Government Agencies and Mortgage-Backed Securities: Fair Value	2,030,281
Held-to-Maturity: Mortgage-Backed Securities: Fair Value	2,036,807
Held-to-Maturity: Fair Value	2,036,807	2,269,761
Commercial - Government Agencies or Sponsored Agencies
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Rolling Maturities [Abstract]
Available-for-sale Securities: Amortized Cost	188,073
Available-for-Sale: Amortized Cost	188,073	155,164
Available-for-sale Securities, Debt Securities Issued by Government Agencies and Mortgage-Backed Securities: Fair Value	180,965
Available-for-Sale: Fair Value	180,965	155,890
Held-to-Maturity Securities, Debt Maturities, Single Maturity Date, Fair Value, Rolling Maturities [Abstract]
Held-to-Maturity: Mortgage-Backed Securities: Amortized Cost	468,145
Held-to-Maturity: Mortgage-Backed Securities: Amortized Cost	468,145
Available-for-sale Securities, Debt Securities Issued by Government Agencies and Mortgage-Backed Securities: Fair Value	180,965
Held-to-Maturity: Mortgage-Backed Securities: Fair Value	427,218
Held-to-Maturity: Fair Value	427,218	469,664
Mortgage-Backed Securities
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Rolling Maturities [Abstract]
Available-for-sale Securities: Amortized Cost	3,757,281
Available-for-Sale: Amortized Cost	3,757,281	3,610,935
Available-for-sale Securities, Debt Securities Issued by Government Agencies and Mortgage-Backed Securities: Fair Value	3,502,396
Available-for-Sale: Fair Value	3,502,396	3,565,258
Held-to-Maturity Securities, Debt Maturities, Single Maturity Date, Fair Value, Rolling Maturities [Abstract]
Held-to-Maturity: Mortgage-Backed Securities: Amortized Cost	4,338,593
Held-to-Maturity: Mortgage-Backed Securities: Amortized Cost	4,338,593
Available-for-sale Securities, Debt Securities Issued by Government Agencies and Mortgage-Backed Securities: Fair Value	3,502,396
Held-to-Maturity: Mortgage-Backed Securities: Fair Value	4,029,999
Held-to-Maturity: Fair Value	$ 4,029,999	$ 4,495,337