Deposits - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Banking and Thrift, Other Disclosures [Abstract]
Deposits	$ 20,890,860		$ 20,890,860		$ 22,666,039
Brokered deposits	11,600,000		11,600,000		11,900,000
Retail and other deposits	9,300,000		9,300,000		10,800,000
Stable interest-bearing deposits, total	7,000,000		7,000,000		7,100,000
Brokered deposit placement fee	4,000	$ 5,000	12,000	$ 15,000
Third party broker fees paid	10,000	$ 2,000	11,000	$ 5,000
Deposits exceeding FDIC insurance limits	676,000		676,000		571,000
Accrued interest on deposits	$ 46,000		$ 46,000		$ 50,000