Accumulated Other Comprehensive Income (Balance of and Changes in Each Component of AOCI) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Accumulated Other Comprehensive Income Loss Net Of Tax [Line Items]
Other Comprehensive Income (Loss), before Tax				$ (700,801)	$ 940,231
Other Comprehensive Income (Loss), Tax				197,414	(293,500)
Net income		$ 130,391	$ 198,296	255,505	334,960
Balance, Beginning of Period				1,657,129	1,005,607
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest		213,790	300,535	397,915	499,975
Balance, End of Period		1,149,364	1,628,660	1,149,364	1,628,660
Provision for income taxes		(83,399)	(102,239)	(142,410)	(165,015)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax				(503,387)	646,731
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Line Items]
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax				(89,220)	(9,162)
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax				(6,616)	9,122
Net income				0	0
Balance, Beginning of Period				81,847	207,083
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest				0	0
Balance, End of Period		(13,989)	207,043	(13,989)	207,043
Provision for income taxes				0	0
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax				(95,836)	(40)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Line Items]
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Reclassification Adjustments and Tax	[1]			(612,314)	949,650
Other Comprehensive Income (Loss), Available-for-sale Securities, before Reclassification Adjustments, Tax	[1]			204,252	(302,873)
Net income	[1]			(5,655)	(24,698)
Balance, Beginning of Period	[1]			1,624,773	820,245
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	[1]			(6,192)	(37,661)
Balance, End of Period	[1]	1,211,056	1,442,324	1,211,056	1,442,324
Provision for income taxes	[1]			537	12,963
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]			(408,062)	646,777
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Line Items]
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, before Tax				733	(257)
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Tax				(222)	251
Net income				1,277	1,020
Balance, Beginning of Period				(49,491)	(21,721)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest				1,965	1,570
Balance, End of Period		$ (47,703)	$ (20,707)	(47,703)	(20,707)
Provision for income taxes				(688)	(550)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax				511	(6)
Amounts Reclassified From AOCI [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Line Items]
Net income				(4,378)	(23,678)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest				(4,227)	(36,091)
Provision for income taxes				$ (151)	$ 12,413

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