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Investments - Gains and Proceeds (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Investments
Realized gain on sale of investments	$ 0	$ 0
Realized loss on sale of investments	0	$ 0
Proceeds from sale of available-for-sale debt securities	$ 0			$ 1,200
Maturities of investments - debt securities			$ 69,000	46,000
Purchases of available-for-sale securities			$ 94,200	108,000
Maximum
Investments
Net realized gains on sale of investments				$ 100