Fair Value of Financial Instruments (Carrying Value and Estimated Fair Value) (Details) - USD ($) $ in Thousands		Jun. 30, 2016	Dec. 31, 2015
Investments
Held-to-maturity securities		$ 660	$ 675
Available-for-sale securities		3,191,544	3,061,208
Trading securities		17,562	16,975
Fair Value [Member]
Investments
Mortgage loans		4,133	4,237
Policy loans		5,282	5,618
Other long-term investments		52,349	54,151
Short-term investments		175	175
Cash and cash equivalents		119,700	106,449
Corporate-owned life insurance		2,208	1,716
Policy reserves
Annuity (accumulations)	[1]	725,769	707,190
Annuity (benefit payments)		142,031	131,899
Fair Value [Member] | Fixed Maturities [Member]
Investments
Held-to-maturity securities		660	675
Available-for-sale securities		2,942,364	2,824,961
Trading securities		12,558	12,622
Fair Value [Member] | Equity Securities [Member]
Investments
Available-for-sale securities		249,180	236,247
Trading securities		5,004	4,353
Carrying Value [Member]
Investments
Mortgage loans		3,836	3,961
Policy loans		5,282	5,618
Other long-term investments		52,349	54,151
Short-term investments		175	175
Cash and cash equivalents		119,700	106,449
Corporate-owned life insurance		2,208	1,716
Policy reserves
Annuity (accumulations)	[1]	708,599	744,931
Annuity (benefit payments)		95,798	95,467
Carrying Value [Member] | Fixed Maturities [Member]
Investments
Held-to-maturity securities		658	672
Available-for-sale securities		2,942,364	2,824,961
Trading securities		12,558	12,622
Carrying Value [Member] | Equity Securities [Member]
Investments
Available-for-sale securities		249,180	236,247
Trading securities		$ 5,004	$ 4,353

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