Equity (Schedule of Reclassifications out of AOCI) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Investment related gains (losses), net		$ 77,712	$ (87,069)
Investment income		514,364	417,266
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest		207,844	107,580
Income Tax Expense (Benefit)		(62,332)	(31,108)
Net income		145,512	76,472
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		(5,762)	(10,237)
Income Tax Expense (Benefit)		3,194	4,649
Net income		(2,568)	(5,588)
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		(11,857)	(18,291)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	[1]	50	788
Unrealized Appreciation Depreciation Of Investments [Member] | Gains Losses On Qualifying Cash Flow Hedging Instruments [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Investment income	[1]	197	160
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	[2]	(5,848)	7,106
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		(1,456)	(1,551)
Income Tax Expense (Benefit)		510	543
Net income		(946)	(1,008)
Amounts Reclassified From AOCI [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net income		(3,514)	(6,596)
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	[3]	82	(78)
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)	[3]	$ 1,538	$ (1,473)

[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 2016 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.