Fair Value of Assets and Liabilities (Narrative) (Details) (USD $)	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2013	Dec. 31, 2012
Total commercial mortgage and other loans		$ 1,476,271,000	$ 1,463,977,000
Other Long-Term Investments		183,475,000	284,489,000
Other liabilities		559,467,000	726,737,000
Embedded Derivative Fair Value of Embedded Derivative		609,000,000	1,441,000,000
Separate Account Assets Invested In Real Estate		79,100,000	77,300,000
Derivative With Fair Value		0	200,000
Equity Securities, AFS Transfered From Level 1 To Level 2	8,600,000
Variation Margin		$ 200,000
High Range [Member]
Capitalization Rates		9.50%	9.50%
Discount Rates		11.00%	11.50%
Low Range [Member]
Capitalization Rates		5.00%	5.50%
Discount Rates		7.00%	7.00%
Weighted Average Rate [Member]
Capitalization Rates		7.08%	7.30%
Discount Rates		8.17%	8.30%