Investment Securities (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Cost
Equity	$ 300,141	$ 262,564
Debt	743,582	613,271
Other	19,444	11,431
Total	1,063,167	887,266
Gains
Equity	253,423	219,658
Debt	6,727	18,090
Other	0	0
Total	260,150	237,748
Losses
Equity	(4,727)	(8,127)
Debt	(3,928)	(641)
Other	0	0
Total	(8,655)	(8,768)
Fair Value
Equity	548,837	474,095
Debt	746,381	630,720
Other	19,444	11,431
Total	$ 1,314,662	$ 1,116,246