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Investment Securities, Equity Securities with Readily Determinable Fair Values and Other Investments - Contractual Maturities and Estimated Fair Values (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Amortized Cost
Due in one year or less, held-to-maturity debt securities amortized cost	$ 1,200,000		$ 1,200,000
Due after one year through five years, held-to-maturity debt securities amortized cost	3,200,000		3,200,000
Amortized cost, held-to-maturity debt securities	4,400,000		4,400,000		$ 3,400,000
Fair Value
Due in one year or less, held-to-maturity debt securities, Estimated fair value	1,200,000		1,200,000
Due after one year through five years, held-to-maturity debt securities, Estimated fair value	3,200,000		3,200,000
Estimated fair value	4,400,000		4,400,000		3,400,000
Available-for-sale debt securities amortized cost disclosures
Due after five years through ten years, available-for-sale debt securities amortized cost	1,450,000		1,450,000
Due after ten years, available-for-sale debt securities amortized cost	157,608,000		157,608,000
Residential mortgage-backed securities, amortized cost	5,251,514,000		5,251,514,000
Amortized cost, Available-for-sale securities	5,410,572,000		5,410,572,000		5,330,814,000
Available for sale debt securities, Estimated Fair Value Disclosures
Due after five years through ten years, available-for-sale debt securities, Estimated Fair Value	1,441,000		1,441,000
Due after ten years, available-for-sale debt securities, Estimated Fair Value	155,163,000		155,163,000
Residential mortgage-backed securities, Estimated Fair Value	4,712,423,000		4,712,423,000
Estimated fair value, Available for sale securities	4,869,027,000		4,869,027,000		$ 4,822,341,000
Available for sale debt securities, Estimated Fair Value Disclosures
Proceeds from sales and calls of available for sale securities	0	$ 0	1,720,000	$ 450,000
Proceeds from sales of mortgage-backed securities	0	0	0	0
Gross gains realized on sales	0	0	0	0
Gross losses realized on sales	0	$ 0	0	$ 0
Collateral Pledged
Available-for-sale debt securities amortized cost disclosures
Amortized cost, Available-for-sale securities	2,001,561,000		2,001,561,000
Available for sale debt securities, Estimated Fair Value Disclosures
Fair value of available for sale investment securities pledged	$ 1,734,388,000		$ 1,734,388,000

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