CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues:
Net premiums	$ 2,594,460	$ 2,480,451	$ 5,177,011	$ 4,846,147
Investment income, net of related expenses	528,061	518,538	1,044,390	1,032,902
Investment related gains (losses), net:
Other-than-temporary impairments on fixed maturity securities	(3,350)	(3,401)	(3,350)	(20,590)
Other investment related gains (losses), net	(7,222)	59,696	(7,692)	137,408
Total investment related gains (losses), net	(10,572)	56,295	(11,042)	116,818
Other revenues	83,959	73,992	159,256	142,149
Total revenues	3,195,908	3,129,276	6,369,615	6,138,016
Benefits and Expenses:
Claims and other policy benefits	2,279,593	2,164,363	4,641,694	4,270,508
Interest credited	109,327	115,285	189,776	222,969
Policy acquisition costs and other insurance expenses	320,276	319,832	677,178	699,221
Other operating expenses	194,959	154,356	386,233	312,862
Interest expense	37,025	29,352	74,479	71,754
Collateral finance and securitization expense	7,440	6,773	15,042	13,543
Total benefits and expenses	2,948,620	2,789,961	5,984,402	5,590,857
Income before income taxes	247,288	339,315	385,213	547,159
Provision for income taxes	42,914	107,125	80,609	169,457
Net income	$ 204,374	$ 232,190	$ 304,604	$ 377,702
Earnings per share:
Basic earnings per share	$ 3.19	$ 3.60	$ 4.74	$ 5.86
Diluted earnings per share	3.13	3.54	4.65	5.76
Dividends declared per share	$ 0.50	$ 0.41	$ 1.00	$ 0.82