Fair Value Measurements, Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financial assets
Cash and due from banks	$ 416,154	$ 373,380
Interest-bearing deposits in other financial institutions	298,759	207,624
Federal funds sold and securities purchased under agreements to resell	1,135	7,740
Investment securities held to maturity	1,879,005	2,205,083
Investment securities held to maturity, fair value	2,028,943	2,276,465
Investment securities available for sale	3,085,441	3,262,586
Equity Securities with Readily Determined Fair Value	2,000	2,000
Equity Securities without Readily Determinable Fair Value, Amount	13,000	13,000
Equity securities	15,106	15,090
FHLB and Federal Reserve Bank stocks	168,280	227,347
Commercial loans held for sale	0	15,000
Loans, net	24,068,022	22,620,068
Bank and Corporate Owned Life Insurance	679,647	671,948
Financial liabilities
Short-term funding	252,317	465,113
Other long-term funding	549,465
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances	1,632,723	3,180,967
Commitment on standby letters of credit	279,000	278,000
Interest rate lock commitments to originate residential mortgage loans held for sale
Financial liabilities
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	9,624	2,527	$ 2,208
Forward commitments to sell residential mortgage loans
Financial liabilities
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	2,046	710	2,072
Total derivatives
Financial liabilities
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	7,579	1,817	$ 140
Fair Value, Inputs, Level 1
Financial assets
Cash and due from banks	416,154	373,380
Cash and due from banks, Fair Value	416,154	373,380
Interest-bearing deposits in other financial institutions	298,759	207,624
Interest-bearing deposits in other financial institutions, fair value	298,759	207,624
Federal funds sold and securities purchased under agreements to resell	1,135	7,740
Federal funds sold and securities purchased under agreements to resell, fair value	1,135	7,740
Investment securities held to maturity	999	999
Investment securities held to maturity, fair value	1,024	1,018
Investment securities available for sale	26,531	0
Investment securities available for sale, at fair value	26,531	0
Equity securities with readily determinable fair value, Carrying Amount	1,661	1,646
Equity Securities with Readily Determined Fair Value	1,661	1,646
Fair Value, Inputs, Level 1 \| U.S. Treasury securities \| Fair Value, Measurements, Recurring [Member]
Financial assets
Investment securities available for sale	26,531	0
Fair Value, Inputs, Level 2
Financial assets
Investment securities held to maturity	1,877,939	2,204,084
Investment securities held to maturity, fair value	2,027,852	2,275,447
Investment securities available for sale	3,058,910	3,262,586
Investment securities available for sale, at fair value	3,058,910	3,262,586
FHLB and Federal Reserve Bank stocks	168,280	227,347
FHLB and Federal Reserve Bank stocks, fair value	168,280	227,347
Residential Loans Receivable Held for sale Net Not Part of Disposal Group	129,158	136,280
Mortgage loans held for sale	129,158	136,280
Residential Held-for-sale, Fair Value Disclosure	129,158	136,280
Commercial loans held for sale	0	15,000
Commercial Loans Held-for-sale, Fair Value Disclosure	0	15,000
Bank and Corporate Owned Life Insurance	679,647	671,948
Bank owned life insurance, fair value	679,647	671,948
Financial liabilities
Brokered CDs and other time deposits	1,757,030	2,622,803
Brokered CDs and other time deposits, fair value	1,766,200	2,622,803
Short-term funding	252,317	465,113
Short-term funding, fair value	252,303	465,113
Other long-term funding	549,465	549,343
Other long -term funding, fair value	578,233
Long-term funding, fair value	1,760,727	572,873
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances	1,632,723	3,180,967
Advances, Fair Value Disclosure		3,207,793
Standby letters of credit	2,731	2,710
Standby letters of credit, fair value	2,731	2,710
Fair Value, Inputs, Level 2 \| GNMA \| Fair Value, Measurements, Recurring [Member]
Financial assets
Investment securities available for sale	235,537	985,139
Fair Value, Inputs, Level 2 \| Commercial mortgage-related securities \| Fair Value, Measurements, Recurring [Member] \| GNMA
Financial assets
Investment securities available for sale	524,756	1,310,207
Fair Value, Inputs, Level 2 \| Asset
Financial assets
Derivative Assets	209,913	101,778
Derivatives (trading and other assets), fair value	209,913	101,778
Fair Value, Inputs, Level 2 \| Liability
Financial liabilities
Net Amounts Presented on the Consolidated Balance Sheets	41,671	36,745
Derivatives (trading and other liabilities), fair value	41,671	36,745
Fair Value, Inputs, Level 3
Financial assets
Equity Securities without Readily Determinable Fair Value, Amount	13,444	13,444
Equity securities	13,444	13,444
Loans, net	24,068,022	22,620,068
Loans, net, fair value	24,012,738	22,399,621
Derivative Assets	9,624	2,527
Derivatives (trading and other assets), fair value	9,624	2,527
Financial liabilities
Noninterest-bearing demand, savings, interest-bearing demand, and money market accounts	24,725,451	21,156,261
Noninterest-bearing demand, savings, interest-bearing demand, and money market accounts, fair value	24,725,451	21,156,261
Net Amounts Presented on the Consolidated Balance Sheets	2,046	710
Derivatives (trading and other liabilities), fair value	$ 2,046	710
Fair Value, Inputs, Level 3 \| Fair Value, Measurements, Nonrecurring
Financial assets
Equity Securities without Readily Determinable Fair Value, Amount		13,444
Equity securities		$ 13,444

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

No definition available.