Investment Securities, Equity Securities with Readily Determinable Fair Values and Other Investments - Contractual Maturities and Estimated Fair Values (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Amortized Cost
Due in one year or less, held-to-maturity debt securities amortized cost	$ 1,325,000		$ 1,325,000
Due after one year through five years, held-to-maturity debt securities amortized cost	3,075,000		3,075,000
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	1,325,000		1,325,000
Due after one year through five years, held-to-maturity debt securities, Estimated fair value	3,075,000		3,075,000
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	1,446,000		1,446,000
Due after ten years, available-for-sale debt securities amortized cost	155,477,000		155,477,000
Residential mortgage-backed securities, available-for-sale debt securities amortized cost	5,253,172,000		5,253,172,000
Amortized cost, Available-for-sale securities	5,410,095,000		5,410,095,000		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	155,535,000		155,535,000
Residential mortgage-backed securities, available-for-sale debt securities, Estimated Fair Value	4,855,608,000		4,855,608,000
Estimated fair value, Available for sale securities	5,012,584,000		5,012,584,000		$ 4,822,341,000
Available for sale debt securities, Estimated Fair Value Disclosures
Proceeds from sales and calls of available for sale securities	2,030,000	$ 1,595,000	3,750,000	$ 2,045,000
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	1	$ 3	1	$ 3
Collateral pledged
Available-for-sale debt securities amortized cost disclosures
Amortized cost, Available-for-sale securities	1,832,243,000		1,832,243,000
Available for sale debt securities, Estimated Fair Value Disclosures
Fair value of available for sale investment securities pledged	$ 1,626,862,000		$ 1,626,862,000