Fair Value of Financial Instruments (Carrying Value and Estimated Fair Value) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Investments
Held-to-maturity fixed maturities	$ 421		$ 669
Available-for-sale securities	3,060,611		2,980,624
Trading securities	20,693		12,427
Fair Value [Member]
Investments
Mortgage loans	4,577		4,724
Policy loans	6,046		6,261
Other long-term investments	46,428		44,946
Short-term investments	500		800
Cash and cash equivalents	71,932		92,193
Corporate-owned life insurance	734		0
Policy reserves
Annuity (accumulations)	925,478	[1]	941,636	[1]
Annuity (benefit payments)	149,980		140,276
Fair Value [Member] | Fixed Maturities [Member]
Investments
Held-to-maturity fixed maturities	421		669
Available-for-sale securities	2,826,643		2,751,256
Trading securities	17,441		9,940
Fair Value [Member] | Equity Securities [Member]
Investments
Available-for-sale securities	233,968		229,368
Trading securities	3,252		2,487
Carrying Value [Member]
Investments
Mortgage loans	4,257		4,423
Policy loans	6,046		6,261
Other long-term investments	46,428		44,946
Short-term investments	500		800
Cash and cash equivalents	71,932		92,193
Corporate-owned life insurance	734		0
Policy reserves
Annuity (accumulations)	887,634	[1]	925,832	[1]
Annuity (benefit payments)	98,492		94,805
Carrying Value [Member] | Fixed Maturities [Member]
Investments
Held-to-maturity fixed maturities	413		656
Available-for-sale securities	2,826,643		2,751,256
Trading securities	17,441		9,940
Carrying Value [Member] | Equity Securities [Member]
Investments
Available-for-sale securities	233,968		229,368
Trading securities	$ 3,252		$ 2,487

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