Investment Securities, Equity Securities with Readily Determinable Fair Values and Other Investments - Contractual Maturities and Estimated Fair Values (Details) - USD ($)	3 Months Ended
Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Amortized Cost
Due in one year or less, held-to-maturity debt securities amortized cost	$ 2,200,000
Due after one year through five years, held-to-maturity debt securities amortized cost	2,200,000
Amortized cost, held-to-maturity debt securities	4,400,000		$ 3,400,000
Fair Value
Due in one year or less, held-to-maturity debt securities, Estimated fair value	2,200,000
Due after one year through five years, held-to-maturity debt securities, Estimated fair value	2,200,000
Estimated fair value	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	1,455,000
Due after ten years, available-for-sale debt securities amortized cost	157,714,000
Residential mortgage-backed securities, amortized cost	5,147,065,000
Amortized cost, Available-for-sale securities	5,306,234,000		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	1,444,000
Due after ten years, available-for-sale debt securities, Estimated Fair Value	155,880,000
Residential mortgage-backed securities, Estimated Fair Value	4,612,306,000
Estimated fair value, Available for sale securities	4,769,630,000		$ 4,822,341,000
Available for sale debt securities, Estimated Fair Value Disclosures
Proceeds from sales and calls of available for sale securities	1,720,000	$ 450,000
Proceeds from sales of mortgage-backed securities	0	0
Gross gains realized on sales	0	0
Gross losses realized on sales	0	$ 0
Collateral Pledged
Available-for-sale debt securities amortized cost disclosures
Amortized cost, Available-for-sale securities	1,821,695,000
Available for sale debt securities, Estimated Fair Value Disclosures
Fair value of available for sale investment securities pledged	$ 1,573,944,000

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Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), without single maturity date and not allocated over maturity grouping.

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Amortized cost excluding accrued interest, before allowance for credit loss, of 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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Amount of cash inflow from sale of investment in mortgage-backed security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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