Deposit Accounts - Deposit Accounts and Weighted Average Interest Rates (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Transaction accounts
Noninterest-bearing checking	$ 6,757,259	$ 6,011,106
Interest-bearing checking	3,493,331	2,913,260
Money market	5,387,168	5,302,073
Savings	419,558	360,896
Certificates of deposit accounts
$250,000 or less	565,272	800,957
Greater than $250,000	493,001	825,885
Total certificates of deposit accounts	1,058,273	1,626,842
Total deposits	$ 17,115,589	$ 16,214,177
Transaction accounts
Noninterest-bearing checking (as a percent)	0.00%	0.00%
Interest-bearing checking (as a percent)	0.02%	0.06%
Money market (as a percent)	0.07%	0.23%
Savings (as a percent)	0.02%	0.09%
Certificates of deposit accounts
Less than $100,000 (as a percent)	0.29%	0.88%
Greater than $250,000 (as a percent)	0.19%	0.88%
Total certificates of deposit accounts (as a percent)	0.24%	0.88%
Total deposits (as a percent)	0.04%	0.18%