Investments Investments (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014 position		Dec. 31, 2013 position		Dec. 31, 2012
Investment Narrative [Line Items]
Available-for-sale Securities, Amortized Cost Basis	$ 14,010,604,000		$ 11,697,394,000
Available-for-sale Securities	14,885,583,000		12,110,755,000
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	932		1,396
Proceeds From Sale Of Available For Sale Securities Sold At Loss	1,016,500,000		1,104,000,000		828,000,000
Available-for-sale Securities, Gross Realized Losses	31,295,000		60,575,000		27,474,000
Securities Sold under Agreements to Repurchase	92,446,000		0
Securities for Reverse Repurchase Agreements	298,466,000		300,350,000
Mortgage Loan Percent Of Invested Assets	7.40%		7.70%
Policy Loans Percent Of Invested Assets	3.50%		3.80%
Funds Withheld At Interest Percent Of Invested Assets	16.10%		17.80%
Percentage Of Total Gross Unrealized Losses	100.00%		100.00%
Funds withheld at interest	5,922,561,000		5,771,467,000
Funds Held Under Reinsurance Agreements Asset Specific Client	4,200,000,000
Other Invested Assets Percent Of Invested Assets	3.30%		4.10%
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	100.00%		100.00%
Assets Sold under Agreements to Repurchase, Repurchase Liability	101,400,000
Securities Sold under Agreements to Repurchase, Fair Value of Collateral	107,158,000		0
Repurchase Agreement Counterparty, Amount at Risk	5,800,000
Non-Income Producing Securities [Member]
Investment Narrative [Line Items]
Available-for-sale Securities, Amortized Cost Basis	42,700,000		38,500,000
Available-for-sale Securities	52,800,000		47,600,000
Canadian Province Of Quebec Securities [Member]
Investment Narrative [Line Items]
Available-for-sale Securities, Amortized Cost Basis	1,006,315,000		1,041,462,000
Available-for-sale Securities	1,599,673,000		1,389,138,000
Reported Value Measurement [Member]
Investment Narrative [Line Items]
Securities Borrowed	201,050,000		93,000,000
Funds withheld at interest	5,897,202,000	[1]	5,948,374,000	[1]
Mortgage Receivable [Member]
Investment Narrative [Line Items]
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	$ 0		$ 0
CALIFORNIA
Investment Narrative [Line Items]
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	18.70%		23.30%

[1] Carrying values presented herein differ from those presented in the consolidated balance sheets because certain items within the respective financial statement caption are embedded derivatives and are measured at fair value on a recurring basis.