Investments (Credit Quality Indicators) (Details) - Commercial Mortgage and Agricultural Loans - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Greater than 1.2X | 0%-59.99%
Credit Quality Indicators [Line Items]
Financing Receivable	$ 284,897	$ 262,853
Greater than 1.2X | 60%-69.99%
Credit Quality Indicators [Line Items]
Financing Receivable	100,842	115,708
Greater than 1.2X | 70%-79.99%
Credit Quality Indicators [Line Items]
Financing Receivable	8,663	25,034
Greater than 1.2X | Greater than 80%
Credit Quality Indicators [Line Items]
Financing Receivable	0	0
Greater than 1.2X | Total commercial mortgage and agricultural property loans
Credit Quality Indicators [Line Items]
Financing Receivable	394,402	403,595
1.0X to 1.2X | 0%-59.99%
Credit Quality Indicators [Line Items]
Financing Receivable	4,042	4,295
1.0X to 1.2X | 60%-69.99%
Credit Quality Indicators [Line Items]
Financing Receivable	460	468
1.0X to 1.2X | 70%-79.99%
Credit Quality Indicators [Line Items]
Financing Receivable	1,835	1,458
1.0X to 1.2X | Greater than 80%
Credit Quality Indicators [Line Items]
Financing Receivable	0	0
1.0X to 1.2X | Total commercial mortgage and agricultural property loans
Credit Quality Indicators [Line Items]
Financing Receivable	6,337	6,221
Less than 1.0X | 0%-59.99%
Credit Quality Indicators [Line Items]
Financing Receivable	1,076	10,489
Less than 1.0X | 60%-69.99%
Credit Quality Indicators [Line Items]
Financing Receivable	0	0
Less than 1.0X | 70%-79.99%
Credit Quality Indicators [Line Items]
Financing Receivable	0	0
Less than 1.0X | Greater than 80%
Credit Quality Indicators [Line Items]
Financing Receivable	0	0
Less than 1.0X | Total commercial mortgage and agricultural property loans
Credit Quality Indicators [Line Items]
Financing Receivable	1,076	10,489
Total | 0%-59.99%
Credit Quality Indicators [Line Items]
Financing Receivable	290,015	277,637
Total | 60%-69.99%
Credit Quality Indicators [Line Items]
Financing Receivable	101,302	116,176
Total | 70%-79.99%
Credit Quality Indicators [Line Items]
Financing Receivable	10,498	26,492
Total | Greater than 80%
Credit Quality Indicators [Line Items]
Financing Receivable	0	0
Total | Total commercial mortgage and agricultural property loans
Credit Quality Indicators [Line Items]
Financing Receivable	$ 401,815	$ 420,305