Condensed Financial Statements of Parent Company - Condensed Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Assets:
Other Assets.	$ 466,923	$ 515,601
Total assets	44,902,024	43,918,696
Corporate and subordinated debentures	391,904	392,275
Other Liabilities.	478,139	443,096
Shareholders' equity	5,533,098	5,074,927	$ 4,802,940	$ 4,647,880
Total liabilities and shareholders' equity	44,902,024	43,918,696
Parent company | Reportable Legal Entities
Assets:
Cash	110,001	89,069
Investment in subsidiaries	5,808,108	5,368,525
Other Assets.	10,016	12,555
Total assets	5,928,125	5,470,149
Corporate and subordinated debentures	391,904	392,275
Other Liabilities.	3,123	2,947
Shareholders' equity	5,533,098	5,074,927
Total liabilities and shareholders' equity	$ 5,928,125	$ 5,470,149