CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenues:
Net premiums	$ 2,480,451	$ 2,346,945	$ 4,846,147	$ 4,503,950
Investment income, net of related expenses	518,538	507,666	1,032,902	924,932
Investment related gains (losses), net:
Other-than-temporary impairments on fixed maturity securities	(3,401)	(846)	(20,590)	(34,663)
Other investment related gains (losses), net	59,696	119,110	137,408	32,041
Total investment related gains (losses), net	56,295	118,264	116,818	(2,622)
Other revenues	73,992	66,193	142,149	125,376
Total revenues	3,129,276	3,039,068	6,138,016	5,551,636
Benefits and Expenses:
Claims and other policy benefits	2,164,363	1,997,502	4,270,508	3,884,266
Interest credited	115,285	95,849	222,969	183,754
Policy acquisition costs and other insurance expenses	319,832	405,681	699,221	639,444
Other operating expenses	154,356	159,895	312,862	317,319
Interest expense	29,352	20,331	71,754	53,138
Collateral finance and securitization expense	6,773	6,587	13,543	12,912
Total benefits and expenses	2,789,961	2,685,845	5,590,857	5,090,833
Income before income taxes	339,315	353,223	547,159	460,803
Provision for income taxes	107,125	117,120	169,457	148,228
Net income	$ 232,190	$ 236,103	$ 377,702	$ 312,575
Earnings per share:
Basic earnings per share	$ 3.60	$ 3.68	$ 5.86	$ 4.86
Diluted earnings per share	3.54	3.64	5.76	4.81
Dividends declared per share	$ 0.41	$ 0.37	$ 0.82	$ 0.74