Investment Securities - Pledged Securities and Concentration Narrative (Details) - USD ($)	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2022	Dec. 31, 2021
Securities in the available-for-sale portfolio in a continuous loss position
Total pledged securities	$ 2,500,000,000	$ 2,500,000,000	$ 2,100,000,000
Securities pledged to secure public deposits	2,280,947,000	2,280,947,000	1,913,369,000
Securities pledged to secure other financial transactions	200,400,000	200,400,000	193,200,000
Concentration of risk
Credit losses recognized on securities	0	0	0
Non-government issuer
Concentration of risk
Securities of issuers in excess of 10% of stockholders' equity	$ 0	$ 0	$ 0