Accumulated Other Comprehensive Income (Balance of and Changes in Each Component of AOCI) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Other Comprehensive Income (Loss), before Tax				$ (1,018,849)	$ 791,174
Other Comprehensive Income (Loss), Tax				244,218	(275,225)
Net income		$ 83,534	$ 157,996	339,039	492,956
Balance, Beginning of Period			1,499,607	1,657,129	1,005,607
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest		140,137	231,815	538,052	731,790
Balance, End of Period		906,479		906,479
Provision for income taxes		(56,603)	(73,819)	(199,013)	(238,834)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax				(774,631)	515,949
Accumulated Translation Adjustment [Member]
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax				(176,562)	(66,167)
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax				(24,778)	(8,980)
Net income				0	0
Balance, Beginning of Period			131,936	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		(119,493)		(119,493)
Provision for income taxes				0	0
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax				(201,340)	(75,147)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Reclassification Adjustments and Tax	[1]			(843,541)	857,802
Other Comprehensive Income (Loss), Available-for-sale Securities, before Reclassification Adjustments, Tax	[1]			269,378	(266,429)
Net income	[1]			21,380	(23,661)
Balance, Beginning of Period	[1]		1,387,957	1,624,773	820,245
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	[1]			34,790	(36,035)
Balance, End of Period	[1]	1,071,990		1,071,990
Provision for income taxes	[1]			(13,410)	12,374
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]			(574,163)	591,373
Accumulated Defined Benefit Plans Adjustment [Member]
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, before Tax				1,254	(461)
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Tax				(382)	184
Net income				2,601	1,712
Balance, Beginning of Period			$ (20,286)	(49,491)	(21,721)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest				4,002	2,634
Balance, End of Period		$ (46,018)		(46,018)
Provision for income taxes				(1,401)	(922)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax				872	(277)
Amounts Reclassified From AOCI [Member]
Net income				23,981	(21,949)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest				38,792	(33,401)
Provision for income taxes				$ (14,811)	$ 11,452

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