Equity (Schedule of Reclassifications out of AOCI) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Investment related gains (losses), net		$ 17,241	$ (470)
Investment income		579,877	516,329
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest		216,564	137,925
Income Tax Expense (Benefit)		(47,057)	(37,695)
Net income		169,507	100,230
Unrealized Appreciation Depreciation Of Investments [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Investment related gains (losses), net		(273)	(14,456)
Deferred policy acquisition costs attributed to unrealized gains and losses	[1]	14,473	(6,592)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest		14,694	(21,274)
Income Tax Expense (Benefit)		(3,006)	4,678
Net income		11,688	(16,596)
Amortization Of Unrealized Pension And Postretirement Benefits [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Prior service cost	[2]	269	246
Actuarial gains/(losses)	[2]	(1,555)	(1,592)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest		(1,286)	(1,346)
Income Tax Expense (Benefit)		270	283
Net income		(1,016)	(1,063)
Amounts Reclassified From AOCI [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net income		10,672	(17,659)
Interest Rate Options [Member] | 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]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	[3]	469	(370)
Currency Swap [Member] | 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]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	[3]	$ 25	$ 144

[1] This AOCI component is included in the computation of the deferred policy acquisition cost. See Note 8 – “Deferred Policy Acquisition Costs” of the 2018 Annual Report for additional details.

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

[3] See Note 5 - “Derivative Instruments” for additional information on cash flow hedges.