Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
	May 07, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Potential net loss due to Large National Healthcare Account			$ 164,832		$ 159,755
Quarterly dividend declared, per share (in usd per share)			$ 0.31	$ 0.31	$ 0.31
Subsequent event
Quarterly dividend declared, per share (in usd per share)	$ 0.05
Specialty P&C | Forecast | Subsequent event
Potential net loss due to Large National Healthcare Account		$ 50,000