Regulatory Capital - Narrative (Details) - USD ($)		3 Months Ended		6 Months Ended		12 Months Ended
	Jan. 01, 2020	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Mar. 31, 2023	Jan. 01, 2023	Mar. 31, 2022	Jan. 01, 2022	Dec. 31, 2021
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Allowance for credit losses		$ 1,364,716,000	$ 1,081,066,000	$ 1,364,716,000	$ 1,081,066,000	$ 1,357,075,000	$ 1,479,306,000		$ 1,227,362,000		$ 1,165,335,000
Liability for unfunded commitments		62,600,000	113,525,000	62,600,000	113,525,000	124,924,000	$ 32,720,000		$ 32,707,000		$ 72,713,000
Unrealized loss				145,000,000		160,000,000
Unrealized loss, tax benefit				46,000,000		$ 52,000,000
Dividends		$ 300,000,000	$ 293,000,000	$ 300,000,000	$ 401,000,000
Accounting Standards Update 2016-13
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Period of deferment	2 years
Percentage amount deferred per year	25.00%
Percentage amount phased in during year								25.00%		25.00%
Allowance for credit losses	$ 1,100,000,000
Liability for unfunded commitments	116,000,000
Deferred tax asset	306,000,000
Reduction to retained earnings	$ 953,000,000