Fair Value of Financial Instruments (Carrying Value and Estimated Fair Value) (Details) - USD ($) $ in Thousands		Sep. 30, 2015	Dec. 31, 2014
Investments
Held-to-maturity securities		$ 291	$ 404
Available-for-sale securities		3,018,106	3,088,922
Trading securities		17,015	20,928
Fair Value [Member]
Investments
Mortgage loans		4,326	4,559
Policy loans		5,569	5,916
Other long-term investments		51,278	50,424
Short-term investments		175	175
Cash and cash equivalents		124,061	90,574
Corporate-owned life insurance		1,545	918
Policy reserves
Annuity (accumulations)	[1]	761,998	865,802
Annuity (benefit payments)		129,683	176,592
Fair Value [Member] | Fixed Maturities [Member]
Investments
Held-to-maturity securities		291	404
Available-for-sale securities		2,790,417	2,843,079
Trading securities		12,918	16,862
Fair Value [Member] | Equity Securities [Member]
Investments
Available-for-sale securities		227,689	245,843
Trading securities		4,097	4,066
Carrying Value [Member]
Investments
Mortgage loans		4,022	4,199
Policy loans		5,569	5,916
Other long-term investments		51,278	50,424
Short-term investments		175	175
Cash and cash equivalents		124,061	90,574
Corporate-owned life insurance		1,545	918
Policy reserves
Annuity (accumulations)	[1]	765,907	863,606
Annuity (benefit payments)		95,017	99,121
Carrying Value [Member] | Fixed Maturities [Member]
Investments
Held-to-maturity securities		289	397
Available-for-sale securities		2,790,417	2,843,079
Trading securities		12,918	16,862
Carrying Value [Member] | Equity Securities [Member]
Investments
Available-for-sale securities		227,689	245,843
Trading securities		$ 4,097	$ 4,066

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