Consolidated Statements of Operations - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenue:
Life premium		$ 2,189,333	$ 2,073,065	$ 1,966,300
Health premium		947,663	925,520	869,440
Other premium		38	135	400
Total premium		3,137,034	2,998,720	2,836,140
Net investment income		806,903	773,951	758,286
Realized investment gains (losses)		(10,683)	(8,791)	23,548
Other income		1,375	2,185	2,121
Total revenue		3,934,629	3,766,065	3,620,095
Benefits and expenses:
Life policyholder benefits		1,479,272	1,374,608	1,301,562
Health policyholder benefits		612,725	602,610	559,817
Other policyholder benefits		36,751	38,994	42,005
Total policyholder benefits		2,128,748	2,016,212	1,903,384
Amortization of deferred acquisition costs		469,063	445,625	415,914
Commissions, premium taxes, and non-deferred acquisition expenses		249,174	237,541	222,463
Other operating expense		232,064	223,858	217,531
Interest expense		83,345	76,642	76,126
Total benefits and expenses		3,162,394	2,999,878	2,835,418
Income before income taxes		772,235	766,187	784,677
Income taxes	[1]	(232,645)	(249,894)	(256,603)
Income from continuing operations		539,590	516,293	528,074
Discontinued operations:
Income from discontinued operations, net of tax		10,189	10,807	14,865
Net income		$ 549,779	$ 527,100	$ 542,939
Basic net income per common share:
Continuing operations (in dollars per share)		$ 4.50	$ 4.13	$ 4.04
Discontinued operations (in dollars per share)		0.08	0.08	0.11
Total basic net income per common share (in dollar per share)		4.58	4.21	4.15
Diluted net income per common share:
Continuing operations (in dollars per share)	[1]	4.41	4.07	3.98
Discontinued operations (in dollars per share)	[1]	0.08	0.09	0.11
Total diluted net income per common share (in dollars per share)	[1]	$ 4.49	$ 4.16	$ 4.09

[1] Certain current year amounts were prospectively adjusted to give effect to the adoption of ASU 2016-09 related to excess tax benefits from stock compensation as described in Note 1—Significant Accounting Policies under "Accounting Pronouncements Adopted in the Current Year."