Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Available for sale securities, amortized cost	$ 2,298,913	$ 2,241,304
Allowance for expected credit losses	552	0
Trading securities, cost	52,357	46,772
Equity Investments, fair value, cost	127,719	227,873
Other investments, portion carried at fair value	$ 37,714	$ 36,018
Common shares, par value (usd per share)	$ 0.01	$ 0.01
Common shares, shares authorized (in shares)	100,000,000	100,000,000
Common shares, shares issued (in shares)	63,214,475	63,117,235
Deferred tax expense (benefit) on accumulated other comprehensive income (loss)	$ 17,488	$ 9,795
Treasury shares, number of shares (in shares)	9,325,180	9,325,180