Equity method investment - Financial Position and Results of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Schedule of Equity Method Investments [Line Items]
Total assets	$ 47,523,790		$ 47,523,790		$ 41,970,021
Total liabilities	41,686,149		41,686,149		36,450,629
Liabilities and Equity	47,523,790		47,523,790		41,970,021
Bankers Healthcare Group, LLC
Schedule of Equity Method Investments [Line Items]
Total assets	4,335,128		4,335,128		4,375,643
Total liabilities	3,705,350		3,705,350		3,821,725
Equity interests	629,778		629,778		553,918
Liabilities and Equity	4,335,128		4,335,128		$ 4,375,643
Revenues	311,276	$ 293,427	924,560	$ 829,986
Net income	$ 48,125	$ 80,088	$ 152,163	$ 257,121