Equity (Schedule of Reclassifications out of AOCI) (Details) - USD ($) $ in Thousands		3 Months Ended				9 Months Ended
		Sep. 30, 2016		Sep. 30, 2015		Sep. 30, 2016		Sep. 30, 2015
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Investment related gains (losses), net		$ 86,624		$ (88,235)		$ 118,665		$ (90,166)
Investment income		489,727		389,597		1,414,659		1,267,027
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest		287,600		140,137		748,403		538,052
Income Tax Expense (Benefit)		(88,881)		(56,603)		(237,109)		(199,013)
Net income		198,719		83,534		511,294		339,039
Unrealized Appreciation Depreciation Of Investments [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest		84,778		(40,982)		109,145		(34,790)
Income Tax Expense (Benefit)		(27,680)		13,948		(32,676)		13,410
Net income		57,098		(27,034)		76,469		(21,380)
Unrealized Appreciation Depreciation Of Investments [Member] | Unrealized Gains Losses On Available For Sale Securities [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Investment related gains (losses), net		72,351		(31,506)		84,250		(26,598)
Unrealized Appreciation Depreciation Of Investments [Member] | Interest Rate Swap [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	[1]	200		(60)		454		231
Unrealized Appreciation Depreciation Of Investments [Member] | Forward Contracts [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	[1]	137		127		(120)		1,094
Unrealized Appreciation Depreciation Of Investments [Member] | DAC Attributed To Unrealized Gains Losses [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Deferred policy acquisition costs attributed to unrealized gains and losses		12,090	[1]	(9,543)	[1]	(24,561)	[2]	(9,517)	[2]
Amortization Of Unrealized Pension And Postretirement Benefits [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest		(786)		(2,037)		(4,253)		(4,002)
Income Tax Expense (Benefit)		276		713		1,489		1,401
Net income		(510)		(1,324)		(2,764)		(2,601)
Amounts Reclassified From AOCI [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net income		56,588		(28,358)		73,705		(23,981)
Prior Service Cost [Member] | Amortization Of Unrealized Pension And Postretirement Benefits [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Prior service cost		391	[2]	(82)	[2]	238	[3]	(245)	[3]
Actuarial Gains Losses [Member] | Amortization Of Unrealized Pension And Postretirement Benefits [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Actuarial gains/(losses)		$ (1,177)	[2]	$ (1,955)	[2]	$ 4,491	[3]	$ (3,757)	[3]

[1] See Note 5 - "Derivative Instruments" for additional information on cash flow hedges.

[2] This AOCI component is included in the computation of the deferred policy acquisition cost. See Note 8 – “Deferred Policy Acquisition Costs” of the 2015 Annual Report for additional details.

[3] This AOCI component is included in the computation of the net periodic pension cost. See Note 10 – “Employee Benefit Plans” for additional details.