Investment Securities, Equity Securities with Readily Determinable Fair Values and Other Investments (Details) - USD ($)	Jun. 30, 2023	Dec. 31, 2022
Held-to-maturity securities
Amortized Value	$ 3,400,000	$ 3,400,000
Estimated fair value	3,400,000	3,400,000
Carrying Value	3,400,000	3,400,000
Available-for-sale securities
Amortized cost	5,285,989,000	5,018,996,000
Gross unrealized gains	2,129,000	4,072,000
Gross unrealized losses	(618,271,000)	(605,272,000)
Estimated fair value, Available for sale securities	4,669,847,000	4,417,796,000
Collateral Pledged
Available-for-sale securities
Amortized cost	1,642,812,000
Estimated Fair Value
Available-for-sale securities
Estimated fair value, Available for sale securities	4,669,847,000	4,417,796,000
Reported Value Measurement
Available-for-sale securities
Estimated fair value, Available for sale securities	4,669,847,000	4,417,796,000
US Treasury Securities
Available-for-sale securities
Amortized cost		49,752,000
Gross unrealized losses		(359,000)
US Treasury Securities \| Estimated Fair Value
Available-for-sale securities
Estimated fair value, Available for sale securities		49,393,000
US Treasury Securities \| Reported Value Measurement
Available-for-sale securities
Estimated fair value, Available for sale securities		49,393,000
Residential mortgage-backed securities
Available-for-sale securities
Amortized cost	5,123,159,000	4,805,735,000
Gross unrealized gains	1,237,000	3,145,000
Gross unrealized losses	(616,284,000)	(599,668,000)
Residential mortgage-backed securities \| Estimated Fair Value
Available-for-sale securities
Estimated fair value, Available for sale securities	4,508,112,000	4,209,212,000
Residential mortgage-backed securities \| Reported Value Measurement
Available-for-sale securities
Estimated fair value, Available for sale securities	4,508,112,000	4,209,212,000
US Government Corporations and Agencies Securities [Member]
Available-for-sale securities
Estimated fair value, Available for sale securities	827,045,000	681,121,000
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Available-for-sale securities
Estimated fair value, Available for sale securities	3,681,067,000	3,528,091,000
States and political subdivisions
Available-for-sale securities
Amortized cost	162,830,000	163,509,000
Gross unrealized gains	892,000	927,000
Gross unrealized losses	(1,987,000)	(5,245,000)
States and political subdivisions \| Estimated Fair Value
Available-for-sale securities
Estimated fair value, Available for sale securities	161,735,000	159,191,000
States and political subdivisions \| Reported Value Measurement
Available-for-sale securities
Estimated fair value, Available for sale securities	161,735,000	159,191,000
Other Debt Obligations
Held-to-maturity securities
Amortized Value	3,400,000	3,400,000
Estimated fair value	3,400,000	3,400,000
Carrying Value	$ 3,400,000	$ 3,400,000

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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