Fair Value of Financial Instruments (Carrying Value and Estimated Fair Value) (Details) - USD ($) $ in Thousands		Mar. 31, 2016	Dec. 31, 2015
Investments
Held-to-maturity securities		$ 667	$ 675
Available-for-sale securities		3,092,982	3,061,208
Trading securities		17,446	16,975
Fair Value [Member]
Investments
Mortgage loans		4,197	4,237
Policy loans		5,348	5,618
Other long-term investments		51,815	54,151
Short-term investments		175	175
Cash and cash equivalents		143,981	106,449
Corporate-owned life insurance		2,160	1,716
Policy reserves
Annuity (accumulations)	[1]	727,595	707,190
Annuity (benefit payments)		137,810	131,899
Fair Value [Member] | Fixed Maturities [Member]
Investments
Held-to-maturity securities		667	675
Available-for-sale securities		2,855,166	2,824,961
Trading securities		13,000	12,622
Fair Value [Member] | Equity Securities [Member]
Investments
Available-for-sale securities		237,816	236,247
Trading securities		4,446	4,353
Carrying Value [Member]
Investments
Mortgage loans		3,899	3,961
Policy loans		5,348	5,618
Other long-term investments		51,815	54,151
Short-term investments		175	175
Cash and cash equivalents		143,981	106,449
Corporate-owned life insurance		2,160	1,716
Policy reserves
Annuity (accumulations)	[1]	728,089	744,931
Annuity (benefit payments)		94,659	95,467
Carrying Value [Member] | Fixed Maturities [Member]
Investments
Held-to-maturity securities		664	672
Available-for-sale securities		2,855,166	2,824,961
Trading securities		13,000	12,622
Carrying Value [Member] | Equity Securities [Member]
Investments
Available-for-sale securities		237,816	236,247
Trading securities		$ 4,446	$ 4,353

[1] Annuity accumulations represent deferred annuity contracts that are currently earning interest.