Fair Value Measurements, Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale		$ 4,332,015
Servicing Asset at Fair Value, Amount	$ 67,015	57,158
Fair Value, Inputs, Level 1
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	116,132	122,957
Fair Value, Inputs, Level 2
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	2,664,671	4,209,058
Fair Value, Inputs, Level 3
Assets, Fair Value Disclosure [Abstract]
Trading assets	4,796	30
Servicing Asset at Fair Value, Amount	67,015	57,259
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	234	0
Fair Value, Inputs, Level 3 | Forward commitments (mortgage)
Assets, Fair Value Disclosure [Abstract]
Trading assets	4,796	30
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	9	0
Derivatives (trading and other liabilities), fair value	9	0
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1 | Available-for-sale Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	116,132	122,957
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1 | Other Debt And Other Equity Securities
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	5,025	4,810
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Federal Family Education Loan Program (FFELP) Guaranteed Loans [Member]
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	168,978	177,325
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | US Government-sponsored Enterprises Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	5,845	6,580
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Other Debt securities
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	2,973	2,994
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Available-for-sale Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	2,664,671	4,209,058
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Residential loans held for sale
Assets, Fair Value Disclosure [Abstract]
Trading assets	91,582	136,638
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Interest rate-related instruments — customer and mirror, net
Assets, Fair Value Disclosure [Abstract]
Trading assets	31,728	83,626
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	112,029	26,231
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Foreign currency exchange forwards
Assets, Fair Value Disclosure [Abstract]
Trading assets	1,986	5,490
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	1,815	5,441
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Commodity contracts
Assets, Fair Value Disclosure [Abstract]
Trading assets	0	1,264
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	0	1,248
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3 | Mortgage banking(a)(b)
Assets, Fair Value Disclosure [Abstract]
Trading assets	0	2,617
Liabilities, Fair Value Disclosure [Abstract]
Trading liabilities	224	0
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3 | Interest Rate Lock Commitments and Forward Commitments Total
Assets, Fair Value Disclosure [Abstract]
Trading assets	4,796	2,647
FNMA / FHLMC | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Commercial mortgage-related securities
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	19,786	350,623
FNMA / FHLMC | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Residential Related Securities
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	1,894,819	2,691,879
Government National Mortgage Association (GNMA) [Member] | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Commercial mortgage-related securities
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	126,760	166,799
Government National Mortgage Association (GNMA) [Member] | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Residential Related Securities
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	58,909	67,780
US Treasury Securities | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	116,132	122,957
US Treasury Securities | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale		122,957
Agency Securities | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	14,200	14,897
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	372,401	400,457
US Government-sponsored Enterprises Debt Securities [Member]
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	5,845
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	0	329,724
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Assets, Fair Value Disclosure [Abstract]
Debt Securities, Available-for-sale	$ 0	$ 329,724