Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fixed maturities, available-for-sale amortized cost	$ 9,504,718	$ 9,448,840
Equity securities, cost	3,234,028	3,266,735
Senior long-term debt and other debt (estimated fair value)	$ 3,587,000	$ 3,907,000