CONSOLIDATED CONDENSED STATEMENTS OF INCOME (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues
Premiums and policy fees	$ 3,297,768	$ 2,981,651	$ 2,814,278
Reinsurance ceded	(1,373,597)	(1,377,195)	(1,345,836)
Net of reinsurance ceded	1,924,171	1,604,456	1,468,442
Net investment income	2,197,724	1,918,081	1,862,332
Realized investment gains (losses):
Derivative financial instruments	(346,878)	188,131	(238,480)
All other investments	205,402	(123,537)	231,035
Other-than-temporary impairment losses	(2,589)	(10,941)	(66,188)
Portion recognized in other comprehensive income (before taxes)	(4,686)	(11,506)	7,302
Net impairment losses recognized in earnings	(7,275)	(22,447)	(58,886)
Other income	430,428	394,315	358,563
Total revenues	4,403,572	3,958,999	3,623,006
Benefits and expenses
Benefits and settlement expenses, net of reinsurance ceded: (2014 - $1,226,307; 2013 - $1,209,783; 2012 - $1,228,425)	2,791,610	2,479,757	2,326,040
Amortization of deferred policy acquisition costs and value of business acquired	257,309	192,898	203,565
Other operating expenses, net of reinsurance ceded: (2014 - $196,923; 2013 - $196,311; 2012 - $196,709)	771,364	695,971	640,430
Total benefits and expenses	3,820,283	3,368,626	3,170,035
Income before income tax	583,289	590,373	452,971
Income tax expense
Current	197,943	21,855	76,186
Deferred	471	175,054	74,333
Total income tax expense	198,414	196,909	150,519
Net Income	$ 384,875	$ 393,464	$ 302,452
Net income - basic (in dollars per share)	$ 4.81	$ 4.96	$ 3.73
Net income - diluted (in dollars per share)	$ 4.73	$ 4.86	$ 3.66
Cash dividends paid per share (in dollars per share)	$ 0.92	$ 0.78	$ 0.7
Average shares outstanding - basic (in shares)	80,065,217	79,395,622	81,066,338
Average shares outstanding - diluted (in shares)	81,375,496	80,925,713	82,723,016