Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue:
Total premium	$ 860,750	$ 819,217	$ 2,564,835	$ 2,456,462
Net investment income	221,627	213,872	658,279	634,930
Realized investment gains (losses)	1,032	12,595	14,796	6,142
Other income	393	331	1,104	1,140
Total revenue	1,083,802	1,046,015	3,239,014	3,098,674
Benefits and expenses:
Life policyholder benefits	396,701	386,445	1,196,616	1,168,383
Health policyholder benefits	162,574	155,774	483,654	470,104
Other policyholder benefits	8,581	9,000	25,852	26,923
Total policyholder benefits	567,856	551,219	1,706,122	1,665,410
Amortization of deferred acquisition costs	129,492	122,334	388,189	370,363
Commissions, premium taxes, and non-deferred acquisition costs	69,632	67,863	208,698	198,011
Other operating expense	74,059	63,019	209,503	187,788
Interest expense	22,433	20,970	66,466	62,825
Total benefits and expenses	863,472	825,405	2,578,978	2,484,397
Income before income taxes	220,330	220,610	660,036	614,277
Income taxes	(41,630)	(67,264)	(123,232)	(183,390)
Income from continuing operations	178,700	153,346	536,804	430,887
Income (loss) from discontinued operations, net of tax	24	(12)	(55)	(3,739)
Net income	$ 178,724	$ 153,334	$ 536,749	$ 427,148
Basic net income (loss) per common share:
Continuing operations (in dollars per share)	$ 1.59	$ 1.32	$ 4.74	$ 3.69
Discontinued operations (in dollars per share)	0.00	0.00	(0.01)	(0.03)
Total basic net income per common share (in dollars per share)	1.59	1.32	4.73	3.66
Diluted net income (loss) per common share:
Continuing operations (in dollars per share)	1.55	1.29	4.64	3.61
Discontinued operations (in dollars per share)	0.00	0.00	0.00	(0.03)
Total diluted net income per common share (in dollars per share)	1.55	1.29	4.64	3.58
Dividends declared per common share (in dollars per share)	$ 0.16	$ 0.15	$ 0.48	$ 0.45
Life premium [Member]
Revenue:
Total premium	$ 605,547	$ 576,223	$ 1,806,384	$ 1,725,896
Health premium [Member]
Revenue:
Total premium	255,201	242,991	758,439	730,557
Other premium [Member]
Revenue:
Total premium	$ 2	$ 3	$ 12	$ 9