Fair Value Measurements, Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024	Dec. 31, 2023
Assets, Fair Value Disclosure [Abstract]
Cash and Due from Banks	$ 490,431	$ 544,059
Interest-bearing Deposits in Banks and Other Financial Institutions	802,251	453,590
Federal Funds Sold and Securities Borrowed or Purchased under Agreements to Resell, Fair Value Disclosure	90	21,955
Debt Securities, Available-for-Sale	5,217,278	4,581,434
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	3,636,139	3,738,747
Debt Securities, Held-to-Maturity, Fair Value	3,182,394	3,185,494
Equity Securities, FV-NI and without Readily Determinable Fair Value	26,000	23,242
FHLB and Federal Reserve Bank stocks	251,642	179,665
Loans and Leases Receivable, Net Amount	30,573,623	29,405,041
Life Insurance, Corporate or Bank Owned, Amount	693,511	689,000
Assets	44,455,863	43,023,068
Liabilities, Fair Value Disclosure
Noninterest-bearing Domestic Deposit, Demand	5,906,251	5,775,657
Deposits	34,881,853	34,648,434
Federal Funds Purchased and Securities Sold under Agreements to Repurchase	399,665	470,369
Short-Term Debt	399,665	470,369
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances	3,220,679	1,853,807
Other Long-Term Debt	594,074	837,635
Liabilities	39,587,565	38,417,506
Standby Letters of Credit [Member]
Liabilities, Fair Value Disclosure
Lending Related Commitments	221,900	253,700
Interest Rate Contract
Assets, Fair Value Disclosure [Abstract]
Derivative Asset	20,441	31,950
Liabilities, Fair Value Disclosure
Derivative Liability	3,256	1,452
Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Cash and Due from Banks	490,431	544,059
Interest-bearing Deposits in Banks and Other Financial Institutions	802,251	453,590
Federal Funds Sold and Securities Borrowed or Purchased under Agreements to Resell, Fair Value Disclosure	90	21,955
Equity Securities, FV-NI	11,000	10,742
Equity Securities, FV-NI and without Readily Determinable Fair Value	26,000	23,242
FHLB and Federal Reserve Bank stocks	251,642	179,665
Loan, Mortgage, Held-for-Sale, Fair Value Disclosure	74,563	646,687
Loan, Held-for-Sale, Fair Value Disclosure		32,634
Loans and Leases Receivable, Net Amount	30,558,859	29,373,557
Loans Receivable, Fair Value Disclosure	29,800,771	28,327,115
Life Insurance, Corporate or Bank Owned, Amount	693,511	689,000
Servicing Asset	85,063	87,683
Assets	41,926,669	40,471,048
Assets, Fair Value Disclosure	40,714,835	38,871,352
Liabilities, Fair Value Disclosure
Noninterest-bearing Domestic Deposit, Demand	5,906,251	5,775,657
Deposits, Savings Deposits	5,380,574	5,133,295
Interest-Bearing Domestic Deposit, Demand	9,136,107	9,124,741
Deposits, Money Market Deposits	6,455,589	6,637,915
Brokered CDs, Carrying Amount	3,956,517	4,276,309
Brokered CDs, Fair Value	3,956,517	4,276,309
Time Deposits, at Carrying Value	4,046,815	3,700,518
Time Deposits	4,046,815	3,700,518
Deposits	34,881,853	34,648,434
Federal Funds Purchased and Securities Sold under Agreements to Repurchase	399,665	470,369
Federal Funds Purchased and Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure	400,172	470,370
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances	3,220,679	1,853,807
Federal Home Loan Bank Borrowings, Fair Value Disclosure	3,220,562	1,852,685
Other Long-Term Debt	594,074	837,635
Long-term Debt, Fair Value	599,184	823,991
Long-Term Line of Credit	2,224	2,546
Liabilities	39,213,059	37,991,364
Liabilities, Fair Value Disclosure	39,218,558	37,976,599
Fair Value, Measurements, Recurring | Interest Rate Lock Commitments [Member]
Assets, Fair Value Disclosure [Abstract]
Derivative Asset	1,129	327
Fair Value, Measurements, Recurring | Commitments [Member]
Assets, Fair Value Disclosure [Abstract]
Derivative Asset		254
Liabilities, Fair Value Disclosure
Derivative Liability	450
Fair Value, Measurements, Recurring | Designated as Hedging Instrument | Interest Rate Contract
Assets, Fair Value Disclosure [Abstract]
Derivative Asset	11,063	2,960
Liabilities, Fair Value Disclosure
Derivative Liability	46	2,976
Fair Value, Measurements, Recurring | Designated as Hedging Instrument | Foreign Exchange Forward [Member]
Assets, Fair Value Disclosure [Abstract]
Foreign Currency Contract, Asset, Fair Value Disclosure	949	2,457
Liabilities, Fair Value Disclosure
Foreign Currency Contracts, Liability, Fair Value Disclosure	866	563
Fair Value, Measurements, Recurring | Not Designated as Hedging Instrument [Member] | Interest Rate Contract
Assets, Fair Value Disclosure [Abstract]
Derivative Asset	74,500	88,541
Liabilities, Fair Value Disclosure
Derivative Liability	110,250	170,928
Fair Value, Measurements, Recurring | Not Designated as Hedging Instrument [Member] | Foreign Exchange Forward [Member]
Assets, Fair Value Disclosure [Abstract]
Foreign Currency Contract, Asset, Fair Value Disclosure	3,200	4,315
Liabilities, Fair Value Disclosure
Foreign Currency Contracts, Liability, Fair Value Disclosure	2,952	4,106
US Treasury Securities
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	995	1,000
Debt Securities, Held-to-Maturity, Fair Value	1,014	999
US Treasury Securities | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	995	1,000
Debt Securities, Held-to-Maturity, Fair Value	1,014	999
US States and Political Subdivisions Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	3,019	3,005
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	1,637,318	1,659,722
Debt Securities, Held-to-Maturity, Fair Value	1,485,396	1,486,642
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	3,019	3,005
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	1,637,318	1,659,662
Debt Securities, Held-to-Maturity, Fair Value	1,485,396	1,486,582
Residential Mortgage-Backed Securities [Member] | US Government Sponsored-Enterprise Insured Loans
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	123,560	110,928
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	836,619	885,476
Debt Securities, Held-to-Maturity, Fair Value	705,725	721,946
Residential Mortgage-Backed Securities [Member] | Government National Mortgage Association (GNMA) [Member]
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	4,862,225	4,227,727
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	40,301	43,693
Debt Securities, Held-to-Maturity, Fair Value	37,871	39,927
Residential Mortgage-Backed Securities [Member] | Fair Value, Measurements, Recurring | US Government Sponsored-Enterprise Insured Loans
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	123,560	110,928
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	836,619	885,476
Debt Securities, Held-to-Maturity, Fair Value	705,725	721,946
Residential Mortgage-Backed Securities [Member] | Fair Value, Measurements, Recurring | Government National Mortgage Association (GNMA) [Member]
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	4,862,225	4,227,727
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	40,301	43,693
Debt Securities, Held-to-Maturity, Fair Value	37,871	39,927
Residential Mortgage-Backed Securities [Member] | Fair Value, Measurements, Recurring | Mortgage-backed Securities, Issued by Private Enterprises [Member]
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	307,569	324,182
Debt Securities, Held-to-Maturity, Fair Value	261,038	266,353
Commercial Mortgage-Backed Securities [Member] | US Government Sponsored-Enterprise Insured Loans
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	16,999	17,000
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	766,482	772,456
Debt Securities, Held-to-Maturity, Fair Value	649,352	623,595
Commercial Mortgage-Backed Securities [Member] | Government National Mortgage Association (GNMA) [Member]
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	109,930	111,475
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	46,855	52,219
Debt Securities, Held-to-Maturity, Fair Value	41,998	46,032
Commercial Mortgage-Backed Securities [Member] | Fair Value, Measurements, Recurring | US Government Sponsored-Enterprise Insured Loans
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	16,999	17,000
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	766,482	772,456
Debt Securities, Held-to-Maturity, Fair Value	649,352	623,595
Commercial Mortgage-Backed Securities [Member] | Fair Value, Measurements, Recurring | Government National Mortgage Association (GNMA) [Member]
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	109,930	111,475
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	46,855	52,219
Debt Securities, Held-to-Maturity, Fair Value	41,998	46,032
Federal Family Education Loan Program (FFELP) Guaranteed Loans [Member]
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	98,198	107,839
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	0
Debt Securities, Held-to-Maturity, Fair Value	0
Federal Family Education Loan Program (FFELP) Guaranteed Loans [Member] | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	98,198	107,839
US Government-sponsored Enterprises Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	348	471
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	0
Debt Securities, Held-to-Maturity, Fair Value	0
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	348	471
Other Debt Obligations | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	3,000	2,989
Available-for-sale Securities [Member] | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	5,217,278	4,581,434
Held-to-maturity Securities [Member] | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	3,636,139	3,738,687
Debt Securities, Held-to-Maturity, Fair Value	3,182,394	3,185,434
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Cash and Due from Banks	490,431	544,059
Interest-bearing Deposits in Banks and Other Financial Institutions	802,251	453,590
Federal Funds Sold and Securities Borrowed or Purchased under Agreements to Resell, Fair Value Disclosure	90	21,955
Equity Securities, FV-NI	10,942	10,670
FHLB and Federal Reserve Bank stocks	0	0
Loan, Mortgage, Held-for-Sale, Fair Value Disclosure	0	0
Loan, Held-for-Sale, Fair Value Disclosure		0
Loans Receivable, Fair Value Disclosure	0	0
Life Insurance, Corporate or Bank Owned, Amount	0	0
Servicing Asset	0	0
Assets, Fair Value Disclosure	1,304,728	1,031,273
Liabilities, Fair Value Disclosure
Noninterest-bearing Domestic Deposit, Demand	0	0
Deposits, Savings Deposits	0	0
Interest-Bearing Domestic Deposit, Demand	0	0
Deposits, Money Market Deposits	0	0
Brokered CDs, Fair Value	0	0
Time Deposits	0	0
Deposits	0	0
Federal Funds Purchased and Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure	0	0
Federal Home Loan Bank Borrowings, Fair Value Disclosure	0	0
Long-term Debt, Fair Value	0	0
Long-Term Line of Credit	0	0
Liabilities, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Interest Rate Lock Commitments [Member]
Assets, Fair Value Disclosure [Abstract]
Derivative Asset	0	0
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Commitments [Member]
Assets, Fair Value Disclosure [Abstract]
Derivative Asset		0
Liabilities, Fair Value Disclosure
Derivative Liability	0
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Designated as Hedging Instrument | Interest Rate Contract
Assets, Fair Value Disclosure [Abstract]
Derivative Asset	0	0
Liabilities, Fair Value Disclosure
Derivative Liability	0	0
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Designated as Hedging Instrument | Foreign Exchange Forward [Member]
Assets, Fair Value Disclosure [Abstract]
Foreign Currency Contract, Asset, Fair Value Disclosure	0	0
Liabilities, Fair Value Disclosure
Foreign Currency Contracts, Liability, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Not Designated as Hedging Instrument [Member] | Interest Rate Contract
Assets, Fair Value Disclosure [Abstract]
Derivative Asset	0	0
Liabilities, Fair Value Disclosure
Derivative Liability	0	0
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Not Designated as Hedging Instrument [Member] | Foreign Exchange Forward [Member]
Assets, Fair Value Disclosure [Abstract]
Foreign Currency Contract, Asset, Fair Value Disclosure	0	0
Liabilities, Fair Value Disclosure
Foreign Currency Contracts, Liability, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 1 | US Treasury Securities | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Held-to-Maturity, Fair Value	1,014	999
Fair Value, Inputs, Level 1 | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	0	0
Debt Securities, Held-to-Maturity, Fair Value	0	0
Fair Value, Inputs, Level 1 | Residential Mortgage-Backed Securities [Member] | Fair Value, Measurements, Recurring | US Government Sponsored-Enterprise Insured Loans
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	0	0
Debt Securities, Held-to-Maturity, Fair Value	0	0
Fair Value, Inputs, Level 1 | Residential Mortgage-Backed Securities [Member] | Fair Value, Measurements, Recurring | Government National Mortgage Association (GNMA) [Member]
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	0	0
Debt Securities, Held-to-Maturity, Fair Value	0	0
Fair Value, Inputs, Level 1 | Residential Mortgage-Backed Securities [Member] | Fair Value, Measurements, Recurring | Mortgage-backed Securities, Issued by Private Enterprises [Member]
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Held-to-Maturity, Fair Value	0	0
Fair Value, Inputs, Level 1 | Commercial Mortgage-Backed Securities [Member] | Fair Value, Measurements, Recurring | US Government Sponsored-Enterprise Insured Loans
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	0	0
Debt Securities, Held-to-Maturity, Fair Value	0	0
Fair Value, Inputs, Level 1 | Commercial Mortgage-Backed Securities [Member] | Fair Value, Measurements, Recurring | Government National Mortgage Association (GNMA) [Member]
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	0	0
Debt Securities, Held-to-Maturity, Fair Value	0	0
Fair Value, Inputs, Level 1 | Federal Family Education Loan Program (FFELP) Guaranteed Loans [Member] | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	0	0
Fair Value, Inputs, Level 1 | US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	0	0
Fair Value, Inputs, Level 1 | Other Debt Obligations | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	0	0
Fair Value, Inputs, Level 1 | Available-for-sale Securities [Member] | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	0	0
Fair Value, Inputs, Level 1 | Held-to-maturity Securities [Member] | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Held-to-Maturity, Fair Value	1,014	999
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Cash and Due from Banks	0	0
Interest-bearing Deposits in Banks and Other Financial Institutions	0	0
Federal Funds Sold and Securities Borrowed or Purchased under Agreements to Resell, Fair Value Disclosure	0	0
Equity Securities, FV-NI	0	0
FHLB and Federal Reserve Bank stocks	251,642	179,665
Loan, Mortgage, Held-for-Sale, Fair Value Disclosure	74,563	646,687
Loan, Held-for-Sale, Fair Value Disclosure		32,634
Loans Receivable, Fair Value Disclosure	0	0
Life Insurance, Corporate or Bank Owned, Amount	693,511	689,000
Servicing Asset	0	0
Assets, Fair Value Disclosure	9,508,086	9,412,129
Liabilities, Fair Value Disclosure
Noninterest-bearing Domestic Deposit, Demand	0	0
Deposits, Savings Deposits	0	0
Interest-Bearing Domestic Deposit, Demand	0	0
Deposits, Money Market Deposits	0	0
Brokered CDs, Fair Value	3,956,517	4,276,309
Time Deposits	4,046,815	3,700,518
Deposits	8,003,332	7,976,827
Federal Funds Purchased and Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure	400,172	470,370
Federal Home Loan Bank Borrowings, Fair Value Disclosure	3,220,562	1,852,685
Long-term Debt, Fair Value	599,184	823,991
Long-Term Line of Credit	2,224	2,546
Liabilities, Fair Value Disclosure	12,339,588	11,304,992
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Foreign Exchange Forward [Member]
Assets, Fair Value Disclosure [Abstract]
Derivative Asset	3,200	4,315
Liabilities, Fair Value Disclosure
Derivative Liability	2,952	4,106
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Interest Rate Lock Commitments [Member]
Assets, Fair Value Disclosure [Abstract]
Derivative Asset	0	0
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Commitments [Member]
Assets, Fair Value Disclosure [Abstract]
Derivative Asset		0
Liabilities, Fair Value Disclosure
Derivative Liability	0
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Designated as Hedging Instrument | Interest Rate Contract
Assets, Fair Value Disclosure [Abstract]
Derivative Asset	11,063	2,960
Liabilities, Fair Value Disclosure
Derivative Liability	46	2,976
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Designated as Hedging Instrument | Foreign Exchange Forward [Member]
Assets, Fair Value Disclosure [Abstract]
Derivative Asset	949	2,457
Foreign Currency Contract, Asset, Fair Value Disclosure	949	2,457
Liabilities, Fair Value Disclosure
Derivative Liability	866	563
Foreign Currency Contracts, Liability, Fair Value Disclosure	866	563
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Not Designated as Hedging Instrument [Member] | Interest Rate Contract
Assets, Fair Value Disclosure [Abstract]
Derivative Asset	74,500	88,541
Liabilities, Fair Value Disclosure
Derivative Liability	110,250	170,928
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Not Designated as Hedging Instrument [Member] | Foreign Exchange Forward [Member]
Assets, Fair Value Disclosure [Abstract]
Foreign Currency Contract, Asset, Fair Value Disclosure	3,200	4,315
Liabilities, Fair Value Disclosure
Foreign Currency Contracts, Liability, Fair Value Disclosure	2,952	4,106
Fair Value, Inputs, Level 2 | US Treasury Securities | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Held-to-Maturity, Fair Value	0	0
Fair Value, Inputs, Level 2 | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	3,019	3,005
Debt Securities, Held-to-Maturity, Fair Value	1,485,396	1,486,582
Fair Value, Inputs, Level 2 | Residential Mortgage-Backed Securities [Member] | Fair Value, Measurements, Recurring | US Government Sponsored-Enterprise Insured Loans
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	123,560	110,928
Debt Securities, Held-to-Maturity, Fair Value	705,725	721,946
Fair Value, Inputs, Level 2 | Residential Mortgage-Backed Securities [Member] | Fair Value, Measurements, Recurring | Government National Mortgage Association (GNMA) [Member]
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	4,862,225	4,227,727
Debt Securities, Held-to-Maturity, Fair Value	37,871	39,927
Fair Value, Inputs, Level 2 | Residential Mortgage-Backed Securities [Member] | Fair Value, Measurements, Recurring | Mortgage-backed Securities, Issued by Private Enterprises [Member]
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Held-to-Maturity, Fair Value	261,038	266,353
Fair Value, Inputs, Level 2 | Commercial Mortgage-Backed Securities [Member] | Fair Value, Measurements, Recurring | US Government Sponsored-Enterprise Insured Loans
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	16,999	17,000
Debt Securities, Held-to-Maturity, Fair Value	649,352	623,595
Fair Value, Inputs, Level 2 | Commercial Mortgage-Backed Securities [Member] | Fair Value, Measurements, Recurring | Government National Mortgage Association (GNMA) [Member]
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	109,930	111,475
Debt Securities, Held-to-Maturity, Fair Value	41,998	46,032
Fair Value, Inputs, Level 2 | Federal Family Education Loan Program (FFELP) Guaranteed Loans [Member] | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	98,198	107,839
Fair Value, Inputs, Level 2 | US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	348	471
Fair Value, Inputs, Level 2 | Other Debt Obligations | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	3,000	2,989
Fair Value, Inputs, Level 2 | Available-for-sale Securities [Member] | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	5,217,278	4,581,434
Fair Value, Inputs, Level 2 | Held-to-maturity Securities [Member] | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Held-to-Maturity, Fair Value	3,181,380	3,184,435
Fair Value, Inputs, Level 3
Assets, Fair Value Disclosure [Abstract]
Equity Securities, FV-NI	58	72	$ 24,769
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Cash and Due from Banks	0	0
Interest-bearing Deposits in Banks and Other Financial Institutions	0	0
Federal Funds Sold and Securities Borrowed or Purchased under Agreements to Resell, Fair Value Disclosure	0	0
Equity Securities, FV-NI	58	72
FHLB and Federal Reserve Bank stocks	0	0
Loan, Mortgage, Held-for-Sale, Fair Value Disclosure	0	0
Loan, Held-for-Sale, Fair Value Disclosure		0
Loans Receivable, Fair Value Disclosure	29,800,771	28,327,115
Life Insurance, Corporate or Bank Owned, Amount	0	0
Servicing Asset	85,063	87,683
Assets, Fair Value Disclosure	29,887,021	28,415,450
Liabilities, Fair Value Disclosure
Noninterest-bearing Domestic Deposit, Demand	5,906,251	5,775,657
Deposits, Savings Deposits	5,380,574	5,133,295
Interest-Bearing Domestic Deposit, Demand	9,136,107	9,124,741
Deposits, Money Market Deposits	6,455,589	6,637,915
Brokered CDs, Fair Value	0	0
Time Deposits	0	0
Deposits	26,878,521	26,671,607
Federal Funds Purchased and Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure	0	0
Federal Home Loan Bank Borrowings, Fair Value Disclosure	0	0
Long-term Debt, Fair Value	0	0
Long-Term Line of Credit	0	0
Liabilities, Fair Value Disclosure	26,878,970	26,671,607
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Interest Rate Lock Commitments [Member]
Assets, Fair Value Disclosure [Abstract]
Derivative Asset	1,129	327
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Commitments [Member]
Assets, Fair Value Disclosure [Abstract]
Derivative Asset		254
Liabilities, Fair Value Disclosure
Derivative Liability	450
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Designated as Hedging Instrument | Interest Rate Contract
Assets, Fair Value Disclosure [Abstract]
Derivative Asset	0	0
Liabilities, Fair Value Disclosure
Derivative Liability	0	0
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Designated as Hedging Instrument | Foreign Exchange Forward [Member]
Assets, Fair Value Disclosure [Abstract]
Foreign Currency Contract, Asset, Fair Value Disclosure	0	0
Liabilities, Fair Value Disclosure
Foreign Currency Contracts, Liability, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Not Designated as Hedging Instrument [Member] | Interest Rate Contract
Assets, Fair Value Disclosure [Abstract]
Derivative Asset	0	0
Liabilities, Fair Value Disclosure
Derivative Liability	0	0
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Not Designated as Hedging Instrument [Member] | Foreign Exchange Forward [Member]
Assets, Fair Value Disclosure [Abstract]
Foreign Currency Contract, Asset, Fair Value Disclosure	0	0
Liabilities, Fair Value Disclosure
Foreign Currency Contracts, Liability, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Not Designated as Hedging Instrument [Member] | Interest Rate Lock Commitments [Member]
Assets, Fair Value Disclosure [Abstract]
Derivative Asset	1,129	580
Fair Value, Inputs, Level 3 | US Treasury Securities | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Held-to-Maturity, Fair Value	0	0
Fair Value, Inputs, Level 3 | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	0	0
Debt Securities, Held-to-Maturity, Fair Value	0	0
Fair Value, Inputs, Level 3 | Residential Mortgage-Backed Securities [Member] | Fair Value, Measurements, Recurring | US Government Sponsored-Enterprise Insured Loans
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	0	0
Debt Securities, Held-to-Maturity, Fair Value	0	0
Fair Value, Inputs, Level 3 | Residential Mortgage-Backed Securities [Member] | Fair Value, Measurements, Recurring | Government National Mortgage Association (GNMA) [Member]
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	0	0
Debt Securities, Held-to-Maturity, Fair Value	0	0
Fair Value, Inputs, Level 3 | Residential Mortgage-Backed Securities [Member] | Fair Value, Measurements, Recurring | Mortgage-backed Securities, Issued by Private Enterprises [Member]
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Held-to-Maturity, Fair Value	0	0
Fair Value, Inputs, Level 3 | Commercial Mortgage-Backed Securities [Member] | Fair Value, Measurements, Recurring | US Government Sponsored-Enterprise Insured Loans
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	0	0
Debt Securities, Held-to-Maturity, Fair Value	0	0
Fair Value, Inputs, Level 3 | Commercial Mortgage-Backed Securities [Member] | Fair Value, Measurements, Recurring | Government National Mortgage Association (GNMA) [Member]
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	0	0
Debt Securities, Held-to-Maturity, Fair Value	0	0
Fair Value, Inputs, Level 3 | Federal Family Education Loan Program (FFELP) Guaranteed Loans [Member] | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	0	0
Fair Value, Inputs, Level 3 | US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	0	0
Fair Value, Inputs, Level 3 | Other Debt Obligations | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	0	0
Fair Value, Inputs, Level 3 | Available-for-sale Securities [Member] | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-Sale	0	0
Fair Value, Inputs, Level 3 | Held-to-maturity Securities [Member] | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Held-to-Maturity, Fair Value	0	0
Fair Value, Inputs, NAV [Member] | Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Equity Securities, FV-NI	$ 15,000	$ 12,500