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, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
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	2,075,000		2,075,000
Amortized cost, held-to-maturity debt securities	3,400,000		3,400,000		$ 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	2,075,000		2,075,000
Estimated fair value	3,400,000		3,400,000		3,400,000
Available-for-sale debt securities amortized cost disclosures
Due after one year through five years, available-for-sale debt securities amortized cost	49,314,000		49,314,000
Due after ten years, available-for-sale debt securities amortized cost	41,390,000		41,390,000
Residential mortgage-backed securities, amortized cost	4,557,327,000		4,557,327,000
Amortized cost, Available-for-sale securities	4,648,031,000		4,648,031,000		4,254,960,000
Available for sale debt securities, Estimated Fair Value Disclosures
Due after one year through five years, available-for-sale debt securities, Estimated Fair Value	48,951,000		48,951,000
Due after ten years, available-for-sale debt securities, Estimated Fair Value	41,478,000		41,478,000
Residential mortgage-backed securities, Estimated Fair Value	4,203,931,000		4,203,931,000
Estimated fair value, Available for sale securities	4,294,360,000		4,294,360,000		$ 4,213,920,000
Available for sale debt securities, Estimated Fair Value Disclosures
Proceeds from sales and calls of available for sale securities	0	$ 355,000	0	$ 2,865,000
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	$ 4,000
Collateral Pledged
Available-for-sale debt securities amortized cost disclosures
Amortized cost, Available-for-sale securities	1,557,395,000		1,557,395,000
Available for sale debt securities, Estimated Fair Value Disclosures
Fair value of available for sale investment securities pledged	$ 1,410,743,000		$ 1,410,743,000