Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Amortized cost on fixed maturities trading investments	$ 3,344,014	$ 2,973,276
Cost - equity security trading investments	769,821	648,282
Cost - short-term investments	253,785	494,060
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	$ 280,032	$ 312,060
Common Stock
Common stock, shares authorized (in shares)	70,000,000
Common stock, shares issued (in shares)	55,358,000
Common stock, shares outstanding (in shares)	55,358,000