Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash Flows From Operating Activities
Net income	$ 89,126	$ 59,137	$ 76,140
Adjustments to reconcile net income to net cash provided by operating activities
Net accretion of bond premium	13,745	14,434	15,291
Depreciation and amortization	6,473	6,891	5,603
Stock-based compensation expense	2,510	1,944	1,777
Net realized investment gains	(2,846)	(7,270)	(8,695)
Net cash flows from trading investments	3,080	(6,855)	3,852
Deferred income tax expense (benefit)	(4,496)	1,926	(368)
Changes in:
Accrued investment income	853	1,934	2,452
Premiums receivable	(27,487)	(30,395)	(30,346)
Deferred policy acquisition costs	(17,165)	(6,417)	(2,690)
Reinsurance receivables	13,283	641	26,948
Prepaid reinsurance premiums	(158)	(472)	(197)
Income taxes receivable	0	1,786	14,750
Other assets	(734)	581	(1,417)
Future policy benefits and losses, claims and loss settlement expenses	77,471	47,928	21,251
Unearned premiums	36,332	38,261	28,814
Accrued expenses and other liabilities	4,095	25,287	8,499
Income taxes payable	(95)	5,012	0
Deferred income taxes	(829)	(249)	6,983
Other, net	(3,160)	(2,813)	(7,156)
Total adjustments	100,872	92,154	85,351
Net cash provided by operating activities	189,998	151,291	161,491
Cash Flows From Investing Activities
Proceeds from sale of available-for-sale investments	11,543	3,091	23,007
Proceeds from call and maturity of held-to-maturity investments	175	260	1,004
Proceeds from call and maturity of available-for-sale investments	658,728	561,434	477,071
Proceeds from short-term and other investments	4,421	2,883	7,170
Purchase of held-to-maturity investments	(450)	0	0
Purchase of available-for-sale investments	(695,351)	(614,044)	(587,412)
Purchase of short-term and other investments	(5,656)	(4,351)	(14,375)
Net purchases and sales of property and equipment	(9,696)	(8,151)	(8,451)
Net cash used in investing activities	(36,286)	(58,878)	(101,986)
Policyholders' account balances
Deposits to investment and universal life contracts	99,486	180,487	150,272
Withdrawals from investment and universal life contracts	(217,905)	(243,997)	(208,827)
Payment of cash dividends	(21,658)	(19,680)	(17,484)
Repurchase of common stock	(2,423)	(12,942)	(1,644)
Issuance of common stock	5,496	2,260	3,393
Tax impact from issuance of common stock	(833)	(160)	(488)
Net cash used in financing activities	(137,837)	(94,032)	(74,778)
Net Change in Cash and Cash Equivalents	15,875	(1,619)	(15,273)
Cash and Cash Equivalents at Beginning of Year	90,574	92,193	107,466
Cash and Cash Equivalents at End of Year	$ 106,449	$ 90,574	$ 92,193