CONSOLIDATED CONDENSED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 108,111	$ 81,495	$ 246,395	$ 155,607
Other comprehensive income (loss):
Change in net unrealized gains (losses) on investments, net of income tax: (three and six months 2019 - $264,523 and $566,586; three and six months 2018 - $(113,653) and $(267,032))	995,112	(427,550)	2,131,443	(1,005,262)
Reclassification adjustment for investment amounts included in net income, net of income tax: (three and six months 2019 - $(84) and $(499); three and six months 2018 - $(1,162) and $(981))	(316)	(4,372)	(1,876)	(3,691)
Change in net unrealized gains (losses) relating to other-than-temporary impaired investments for which a portion has been recognized in earnings, net of income tax: (three and six months 2019 - $4,127 and $6,464; three and six months 2018 - $3 and $6)	15,524	11	24,316	22
Change in accumulated (loss) gain - derivatives, net of income tax: (three and six months 2019 - $(742) and $(1,264); three and six months 2018 - $623 and $752)	(2,788)		(4,754)
Change in accumulated (loss) gain - derivatives, net of income tax: (three and six months 2019 - $(742) and $(1,264); three and six months 2018 - $623 and $752)		2,344		2,831
Reclassification adjustment for derivative amounts included in net income, net of income tax: (three and six months 2019 - $70 and $128; three and six months 2018 - $43 and $67)	266		486
Reclassification adjustment for derivative amounts included in net income, net of income tax: (three and six months 2019 - $70 and $128; three and six months 2018 - $43 and $67)		162		251
Total other comprehensive income (loss)	1,007,798	(429,405)	2,149,615	(1,005,849)
Total comprehensive income (loss)	$ 1,115,909	$ (347,910)	$ 2,396,010	$ (850,242)