Fair Value of Financial Instruments (Carrying Value and Estimated Fair Value) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Fair Value [Member]
Investments
Held-to-maturity fixed maturities	$ 1,883		$ 4,161
Available-for-sale fixed maturities	2,830,707		2,697,248
Equity securities	179,724		159,451
Trading securities	14,498		13,454
Mortgage loans	5,157		5,219
Policy loans	7,308		7,209
Other long-term investments	29,499		20,574
Short-term investments	800		1,100
Cash and cash equivalents	82,566		144,527
Accrued investment income	31,229		32,219
Policy reserves
Annuity (accumulations)	1,143,235	[1]	1,074,661	[1]
Annuity (benefit payments)	143,195		133,921
Debt	0		45,000
Carrying Value [Member]
Investments
Held-to-maturity fixed maturities	1,847		4,143
Available-for-sale fixed maturities	2,830,707		2,697,248
Equity securities	179,724		159,451
Trading securities	14,498		13,454
Mortgage loans	4,683		4,829
Policy loans	7,308		7,209
Other long-term investments	29,499		20,574
Short-term investments	800		1,100
Cash and cash equivalents	82,566		144,527
Accrued investment income	31,229		32,219
Policy reserves
Annuity (accumulations)	1,035,062	[1]	999,534	[1]
Annuity (benefit payments)	97,746		94,465
Debt	$ 0		$ 45,000

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