Fair Value of Financial Instruments (Carrying Value and Estimated Fair Value) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Investments
Held-to-maturity fixed maturities	$ 656		$ 669
Available-for-sale securities	3,038,100		2,980,624
Trading securities	19,132		12,427
Fair Value [Member]
Investments
Mortgage loans	4,724		4,724
Policy loans	6,177		6,261
Other long-term investments	46,513		44,946
Short-term investments	800		800
Cash and cash equivalents	68,663		92,193
Policy reserves
Annuity (accumulations)	954,214	[1]	941,636	[1]
Annuity (benefit payments)	142,900		140,276
Fair Value [Member] | Fixed Maturities [Member]
Investments
Held-to-maturity fixed maturities	656		669
Available-for-sale securities	2,805,723		2,751,256
Trading securities	16,095		9,940
Fair Value [Member] | Equity Securities [Member]
Investments
Available-for-sale securities	232,377		229,368
Trading securities	3,037		2,487
Carrying Value [Member]
Investments
Mortgage loans	4,368		4,423
Policy loans	6,177		6,261
Other long-term investments	46,513		44,946
Short-term investments	800		800
Cash and cash equivalents	68,663		92,193
Policy reserves
Annuity (accumulations)	920,038	[1]	925,832	[1]
Annuity (benefit payments)	94,163		94,805
Carrying Value [Member] | Fixed Maturities [Member]
Investments
Held-to-maturity fixed maturities	644		656
Available-for-sale securities	2,805,723		2,751,256
Trading securities	16,095		9,940
Carrying Value [Member] | Equity Securities [Member]
Investments
Available-for-sale securities	232,377		229,368
Trading securities	$ 3,037		$ 2,487

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