Investments - Net Investment Income (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Investment fees and expenses	$ (11,121)	$ (6,385)	$ (6,484)
Net investment income	70,522	71,998	93,269
Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Investment income	74,437	69,308	72,593
Equities
Debt Securities, Available-for-sale [Line Items]
Investment income	2,539	4,369	17,650
Short-term investments, including Other
Debt Securities, Available-for-sale [Line Items]
Investment income	1,969	2,683	7,493
BOLI
Debt Securities, Available-for-sale [Line Items]
Investment income	$ 2,698	$ 2,023	$ 2,017

Represents the total of interest and dividend income, including any amortization and accretion (as applicable) of discounts and premiums, earned from (1) loans and leases whether held-for-sale or held-in-portfolio; (2) investment securities; (3) federal funds sold; (4) securities purchased under agreements to resell; (5) investments in banker's acceptances, commercial paper, or certificates of deposit; (6) dividend income; or (7) other investments not otherwise specified herein.

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