Investments (Mortgage Loans by Real Estate Geographic Location) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Mortgage Loans On Real Estate Geographic Location Of Property [Line Items]
Recorded investment	$ 2,565,492	$ 2,496,786
Percentage of total	100.00%	100.00%
Pacific
Mortgage Loans On Real Estate Geographic Location Of Property [Line Items]
Recorded investment	700,541	671,822
Percentage of total	27.30%	26.90%
South Atlantic
Mortgage Loans On Real Estate Geographic Location Of Property [Line Items]
Recorded investment	504,450	543,658
Percentage of total	19.70%	21.80%
Mountain
Mortgage Loans On Real Estate Geographic Location Of Property [Line Items]
Recorded investment	420,661	334,446
Percentage of total	16.40%	13.40%
Middle Atlantic
Mortgage Loans On Real Estate Geographic Location Of Property [Line Items]
Recorded investment	245,746	266,802
Percentage of total	9.60%	10.70%
West North Central
Mortgage Loans On Real Estate Geographic Location Of Property [Line Items]
Recorded investment	171,018	138,442
Percentage of total	6.70%	5.50%
East North Central
Mortgage Loans On Real Estate Geographic Location Of Property [Line Items]
Recorded investment	232,235	236,766
Percentage of total	9.00%	9.50%
West South Central
Mortgage Loans On Real Estate Geographic Location Of Property [Line Items]
Recorded investment	159,300	168,246
Percentage of total	6.20%	6.70%
East South Central
Mortgage Loans On Real Estate Geographic Location Of Property [Line Items]
Recorded investment	58,986	59,625
Percentage of total	2.30%	2.40%
New England
Mortgage Loans On Real Estate Geographic Location Of Property [Line Items]
Recorded investment	$ 72,555	$ 76,979
Percentage of total	2.80%	3.10%