Segment and Other Operating Information - Net Earnings (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Segment Reporting Information [Line Items]
Net earnings	$ 30,765	$ 49,899	$ 66,949	$ 112,028
Segments
Segment Reporting Information [Line Items]
Net earnings	29,370	47,202	62,557	108,212
Segment Reconciling Items
Segment Reporting Information [Line Items]
Realized gains on investments, net of taxes	$ 1,395	$ 2,697	$ 4,392	$ 3,816