Investments (Credit Quality Indicators) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Credit Quality Indicators [Line Items]
Financing Receivable	$ 447,269	$ 438,815
Greater than 1.2X | 0%-59.99% | Commercial Mortgage and Agricultural Loans
Credit Quality Indicators [Line Items]
Financing Receivable	304,569	303,215
Greater than 1.2X | 60%-69.99% | Commercial Mortgage and Agricultural Loans
Credit Quality Indicators [Line Items]
Financing Receivable	98,855	95,977
Greater than 1.2X | 70%-79.99% | Commercial Mortgage and Agricultural Loans
Credit Quality Indicators [Line Items]
Financing Receivable	34,164	25,401
Greater than 1.2X | Greater than 80% | Commercial Mortgage and Agricultural Loans
Credit Quality Indicators [Line Items]
Financing Receivable	0	0
Greater than 1.2X | Total commercial mortgage and agricultural property loans | Commercial Mortgage and Agricultural Loans
Credit Quality Indicators [Line Items]
Financing Receivable	437,588	424,593
1.0X to 1.2X | 0%-59.99% | Commercial Mortgage and Agricultural Loans
Credit Quality Indicators [Line Items]
Financing Receivable	4,628	9,073
1.0X to 1.2X | 60%-69.99% | Commercial Mortgage and Agricultural Loans
Credit Quality Indicators [Line Items]
Financing Receivable	0	0
1.0X to 1.2X | 70%-79.99% | Commercial Mortgage and Agricultural Loans
Credit Quality Indicators [Line Items]
Financing Receivable	1,406	1,417
1.0X to 1.2X | Greater than 80% | Commercial Mortgage and Agricultural Loans
Credit Quality Indicators [Line Items]
Financing Receivable	0	0
1.0X to 1.2X | Total commercial mortgage and agricultural property loans | Commercial Mortgage and Agricultural Loans
Credit Quality Indicators [Line Items]
Financing Receivable	6,034	10,490
Less than 1.0X | 0%-59.99% | Commercial Mortgage and Agricultural Loans
Credit Quality Indicators [Line Items]
Financing Receivable	907	992
Less than 1.0X | 60%-69.99% | Commercial Mortgage and Agricultural Loans
Credit Quality Indicators [Line Items]
Financing Receivable	0	0
Less than 1.0X | 70%-79.99% | Commercial Mortgage and Agricultural Loans
Credit Quality Indicators [Line Items]
Financing Receivable	0	0
Less than 1.0X | Greater than 80% | Commercial Mortgage and Agricultural Loans
Credit Quality Indicators [Line Items]
Financing Receivable	0	0
Less than 1.0X | Total commercial mortgage and agricultural property loans | Commercial Mortgage and Agricultural Loans
Credit Quality Indicators [Line Items]
Financing Receivable	907	992
Total | 0%-59.99% | Commercial Mortgage and Agricultural Loans
Credit Quality Indicators [Line Items]
Financing Receivable	310,104	313,280
Total | 60%-69.99% | Commercial Mortgage and Agricultural Loans
Credit Quality Indicators [Line Items]
Financing Receivable	98,855	95,977
Total | 70%-79.99% | Commercial Mortgage and Agricultural Loans
Credit Quality Indicators [Line Items]
Financing Receivable	35,570	26,818
Total | Greater than 80% | Commercial Mortgage and Agricultural Loans
Credit Quality Indicators [Line Items]
Financing Receivable	0	0
Total | Total commercial mortgage and agricultural property loans | Commercial Mortgage and Agricultural Loans
Credit Quality Indicators [Line Items]
Financing Receivable	$ 444,529	$ 436,075