Fair Value of Financial Instruments (Carrying Value and Estimated Fair Value) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Investments
Held-to-maturity securities	$ 150	$ 150
Available-for-sale, debt securities	1,563,996	1,535,070
Available-for-sale, equity securities		280,913
Trading securities	15,379	16,842
Equity securities	280,362	287,344
Discontinued Operations
Investments
Held-to-maturity securities	0	34
Available-for-sale, debt securities	0	1,430,025
Available-for-sale, equity securities		23,653
Fair Value
Investments
Held-to-maturity securities	150	150
Available-for-sale, debt securities	1,563,996	1,535,070
Trading securities	15,379	16,842
Equity securities	280,362	287,344
Other long-term investments	44,998	49,352
Short-term investments	175	175
Cash and cash equivalents	316,852	95,562
Corporate-owned life insurance	4,404	4,029
Fair Value | Discontinued Operations
Investments
Held-to-maturity securities	0	34
Available-for-sale, debt securities	0	1,430,025
Available-for-sale, equity securities	0	23,653
Mortgage loans	0	3,594
Policy loans	0	5,815
Other long-term investments	0	16,437
Cash and cash equivalents	0	15,851
Policy reserves
Annuity (accumulations)	0	591,702
Annuity (benefit payments)	0	147,038
Carrying Value
Investments
Held-to-maturity securities	150	150
Available-for-sale, debt securities	1,563,996	1,535,070
Trading securities	15,379	16,842
Equity securities	280,362	287,344
Other long-term investments	44,998	49,352
Short-term investments	175	175
Cash and cash equivalents	316,852	95,562
Corporate-owned life insurance	4,404	4,029
Carrying Value | Discontinued Operations
Investments
Held-to-maturity securities	0	34
Available-for-sale, debt securities	0	1,430,025
Available-for-sale, equity securities	0	23,653
Mortgage loans	0	3,435
Policy loans	0	5,815
Other long-term investments	0	16,437
Cash and cash equivalents	0	15,851
Policy reserves
Annuity (accumulations)	0	611,866
Annuity (benefit payments)	$ 0	$ 93,560