Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fixed maturities, available-for-sale amortized cost	$ 9,601,898	$ 9,950,773
Equity securities, cost	3,204,316	2,971,856
Senior long-term debt and other debt (estimated fair value)	$ 4,257,000	$ 3,030,000