Fair Value of Financial Instruments (Carrying Value and Estimated Fair Value) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Investments
Held-to-maturity fixed maturities	$ 1,120		$ 1,681
Available-for-sale securities	2,977,620		2,985,205
Trading securities	12,441		15,371
Fair Value [Member]
Investments
Mortgage loans	4,278		5,037
Policy loans	6,361		6,671
Other long-term investments	34,876		30,028
Short-term investments	800		800
Cash and cash equivalents	86,691		107,466
Accrued investment income	29,064		30,375
Policy reserves
Annuity (accumulations)	965,177	[1]	1,043,866	[1]
Annuity (benefit payments)	137,358		139,213
Fair Value [Member] | Fixed Maturities [Member]
Investments
Held-to-maturity fixed maturities	1,120		1,681
Available-for-sale securities	2,769,082		2,808,078
Trading securities	9,977		13,353
Fair Value [Member] | Equity Securities [Member]
Investments
Available-for-sale securities	208,538		177,127
Trading securities	2,464		2,018
Carrying Value [Member]
Investments
Mortgage loans	4,477		4,633
Policy loans	6,361		6,671
Other long-term investments	34,876		30,028
Short-term investments	800		800
Cash and cash equivalents	86,691		107,466
Accrued investment income	29,064		30,375
Policy reserves
Annuity (accumulations)	935,869	[1]	983,579	[1]
Annuity (benefit payments)	93,695		93,701
Carrying Value [Member] | Fixed Maturities [Member]
Investments
Held-to-maturity fixed maturities	1,102		1,655
Available-for-sale securities	2,769,082		2,808,078
Trading securities	9,977		13,353
Carrying Value [Member] | Equity Securities [Member]
Investments
Available-for-sale securities	208,538		177,127
Trading securities	$ 2,464		$ 2,018

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