Investments - Additional Information (Details) $ in Thousands	1 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2020	Sep. 30, 2021 USD ($) security	Dec. 31, 2020 USD ($) security
Investments, Debt and Equity Securities [Abstract]
Vertical risk retention interest	5.00%	5.00%
Trading investments		$ 36,792	$ 16,923
Number of mortgage-backed securities with unrealized losses | security		38	14
Number of mortgage-backed securities | security		177	163
Par value of mortgage-backed securities pledged to FRB		$ 645,000	$ 815,000
Gain on earlier equity securities investments		35,000
Non-marketable securities investment		69,000	26,000
Low income housing tax credit investments		69,000	54,000
Low income housing tax credit investments, liability for unfunded commitments		33,000	19,000
Low income housing tax credit investments, tax credits and benefits		$ 1,000	$ 6,000
Low income housing tax credit investments, expected tax benefits recognized		25.00%