Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash Flows From Operating Activities
Net income	$ 49,904	$ 89,126	$ 59,137
Adjustments to reconcile net income to net cash provided by operating activities
Net accretion of bond premium	14,097	13,745	14,434
Depreciation and amortization	6,035	6,473	6,891
Stock-based compensation expense	3,696	2,510	1,944
Net realized investment gains	(6,103)	(2,846)	(7,270)
Net cash flows from trading investments	(2,390)	3,080	(6,855)
Deferred income tax expense (benefit)	4,482	(4,496)	1,926
Changes in:
Accrued investment income	80	853	1,934
Premiums receivable	(29,685)	(27,487)	(30,395)
Deferred policy acquisition costs	(258)	(17,165)	(6,417)
Reinsurance receivables	4,114	13,283	641
Prepaid reinsurance premiums	8	(158)	(472)
Income taxes receivable	(15,061)	0	1,786
Other assets	828	(734)	581
Future policy benefits and losses, claims and loss settlement expenses	176,492	77,471	47,928
Unearned premiums	28,816	36,332	38,261
Accrued expenses and other liabilities	(6,054)	4,095	25,287
Income taxes payable	(4,917)	(95)	5,012
Deferred income taxes	1,043	(829)	(249)
Other, net	(10,743)	(3,160)	(2,813)
Total adjustments	164,480	100,872	92,154
Net cash provided by operating activities	214,384	189,998	151,291
Cash Flows From Investing Activities
Proceeds from sale of available-for-sale investments	14,322	11,543	3,091
Proceeds from call and maturity of held-to-maturity investments	516	175	260
Proceeds from call and maturity of available-for-sale investments	533,784	658,728	561,434
Proceeds from short-term and other investments	2,456	4,421	2,883
Purchase of held-to-maturity investments	(42)	(450)	0
Purchase of available-for-sale investments	(651,365)	(695,351)	(614,044)
Purchase of short-term and other investments	(4,474)	(5,656)	(4,351)
Net purchases and sales of property and equipment	(7,600)	(9,696)	(8,151)
Net cash used in investing activities	(112,403)	(36,286)	(58,878)
Policyholders' account balances
Deposits to investment and universal life contracts	79,815	99,486	180,487
Withdrawals from investment and universal life contracts	(158,161)	(217,905)	(243,997)
Payment of cash dividends	(24,591)	(21,658)	(19,680)
Repurchase of common stock	(3,746)	(2,423)	(12,942)
Issuance of common stock	9,922	5,496	2,260
Tax impact from issuance of common stock	(816)	(833)	(160)
Net cash used in financing activities	(97,577)	(137,837)	(94,032)
Net Change in Cash and Cash Equivalents	4,404	15,875	(1,619)
Cash and Cash Equivalents at Beginning of Year	106,449	90,574	92,193
Cash and Cash Equivalents at End of Year	$ 110,853	$ 106,449	$ 90,574