Investments (Commercial Mortgage and Other Loans) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Commercial mortgage loans	$ 347,821	$ 379,132
Commercial mortgage loans, Percentage	86.30%	88.30%
Valuation allowance	(1,769)	(2,177)
Total net commercial and agricultural mortgage loans by property type	401,463	426,981
Total commercial mortgage and other loans, net of valuation allowance	404,203	426,981
Total Commercial Mortgage By Propterty Type	403,232	429,158
Other Loans and Leases Receivable	2,740	0
Office buildings [Member]
Commercial mortgage loans	41,242	59,074
Commercial mortgage loans, Percentage	10.20%	13.80%
Retail stores [Member]
Commercial mortgage loans	72,727	71,546
Commercial mortgage loans, Percentage	18.00%	16.70%
Apartment Complexes [Member]
Commercial mortgage loans	123,727	120,066
Commercial mortgage loans, Percentage	30.70%	28.00%
Industrial Buildings [Member]
Commercial mortgage loans	92,549	114,619
Commercial mortgage loans, Percentage	23.00%	26.70%
Agricultural Properties [Member]
Commercial mortgage loans	55,411	50,026
Commercial mortgage loans, Percentage	13.70%	11.70%
Hospitality [Member]
Commercial mortgage loans	5,144	4,621
Commercial mortgage loans, Percentage	1.30%	1.10%
Other [Member]
Commercial mortgage loans	12,432	9,206
Commercial mortgage loans, Percentage	3.10%	2.00%
California [Member]
Commercial mortgage loans, Percentage	19.00%
Ohio [Member]
Commercial mortgage loans, Percentage	9.00%
New York [Member]
Commercial mortgage loans, Percentage	8.00%
Total Percentage [Member]
Commercial mortgage loans, Percentage	100.00%	100.00%
Uncollateralized Loans [Member]
Other Loans and Leases Receivable	$ 2,740	$ 0
Texas [Member]
Commercial mortgage loans, Percentage	11.00%