Reinsurance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Life Insurance in Force, Gross Amount	$ 16,504,539	$ 15,800,701	$ 15,102,466
Life Insurance in Force, Ceded to Other Companies	3,625,946	3,360,016	3,231,421
Life Insurance in Force, Assumed from Other Companies	0	0	0
Life Insurance in Force, Net Amount	$ 12,878,593	$ 12,440,685	$ 11,871,045
Life Insurance in Force, Percentage of Amount Assumed to Net	0.00%	0.00%	0.00%
Premiums
Gross Amount	$ 752,798	$ 739,281	$ 717,494
Ceded to Other Companies	25,077	27,276	29,990
Assumed from Other Companies	4,159	3,755	3,434
Net Amount	$ 731,880	$ 715,760	$ 690,938
Percentage of Amount Assumed to Net	0.60%	0.50%	0.50%
Property and casualty [Member]
Premiums
Gross Amount	$ 610,347	$ 599,230	$ 582,780
Ceded to Other Companies	18,548	21,157	24,260
Assumed from Other Companies	4,159	3,755	3,434
Net Amount	$ 595,958	$ 581,828	$ 561,954
Percentage of Amount Assumed to Net	0.70%	0.60%	0.60%
Annuity [Member]
Premiums
Gross Amount	$ 25,378	$ 25,540	$ 22,575
Ceded to Other Companies	0	0	0
Assumed from Other Companies	0	0	0
Net Amount	$ 25,378	$ 25,540	$ 22,575
Percentage of Amount Assumed to Net	0.00%	0.00%	0.00%
Life [Member]
Premiums
Gross Amount	$ 117,073	$ 114,511	$ 112,139
Ceded to Other Companies	6,529	6,119	5,730
Assumed from Other Companies	0	0	0
Net Amount	$ 110,544	$ 108,392	$ 106,409
Percentage of Amount Assumed to Net	0.00%	0.00%	0.00%