CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Comprehensive income
Net Income (Loss) Attributable to Parent	$ 1,822,181	$ 701,443	$ 502,166
Other comprehensive income (loss), net of tax:
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	69,126	8,610	(262,998)
Net unrealized investment gains (losses)	698,078	419,336	(689,076)
Change in other-than-temporary impairment losses on fixed maturity securities	(244)	(947)
Defined benefit pension and postretirement plan adjustments	726	3,099	3,229
Total other comprehensive income (loss), net of tax	767,930	431,045	(948,845)
Total comprehensive income (loss)	$ 2,590,111	$ 1,132,488	$ (446,679)