INVESTMENTS Debt Securities and Common Stock (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) security position	Mar. 31, 2018 USD ($) security
Securities in unrealized loss positions
Other-than-temporary impairment (OTTI) losses		$ 56
Equity Securities, FV-NI, Unrealized Gain (Loss)	$ 33,498	$ (26,772)
Debt securities
Securities in unrealized loss positions
Number of unrealized loss positions | position	481
Number of securities in unrealized loss positions for 12 months or longer | security	259
Unrealized losses as percentage of fixed income portfolio cost basis	0.60%
Number of securities with OTTI losses recognized in earnings | security		1
Other-than-temporary Impairment Loss, Debt Securities, Available-for-sale, Recognized in Earnings	$ 0	$ 100
Other than Temporary Impairment Losses recognized in other comprehensive earnings	0	0
Equity securities
Securities in unrealized loss positions
Equity Securities, FV-NI, Unrealized Gain (Loss)	$ 41,900	$ (12,300)