CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 103,514	$ 95,686	$ 176,719	$ 115,542
Other comprehensive income (loss), net of tax:
Unrealized investment gains (losses) arising during the period	(105,280)	76,243	(217,434)	143,953
Adjustment for reclassification of net realized investment gains (losses) and OTTI losses recognized in net income	36,456	(1,503)	37,240	23,458
Unrealized investment gains (losses) arising during the period, net of reclassification adjustment	(68,824)	74,740	(180,194)	167,411
Foreign currency translation adjustment	(9,129)	8,867	(7,858)	38,736
Total other comprehensive income (loss), net of tax	(77,953)	83,607	(188,052)	206,147
Comprehensive income (loss)	$ 25,561	$ 179,293	$ (11,333)	$ 321,689