Investments Allowance for Expected Credit Losses (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($)
Marketable Securities
Credit losses on securities with no previously recorded credit losses	$ 2,510
Balance	2,510
Corporate and other securities
Marketable Securities
Balance	0
Credit losses on securities with no previously recorded credit losses	2,510
Balance	$ 2,510