Equity (Balance of and Changes in Each Component of AOCI) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
Balance, beginning of year		$ 708,284	$ 1,657,129	$ 1,005,607
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax		675,627	(1,349,528)	1,037,395
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		(63,800)	78,998	(28,949)
Other Comprehensive Income (Loss), Tax		(180,782)	321,685	(356,924)
Balance, end of year		1,139,329	708,284	1,657,129
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
Balance, beginning of year		(181,151)	81,847	207,083
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax		29,691	(246,520)	(102,238)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		0	0	0
Other Comprehensive Income (Loss), Tax		(21,081)	(16,478)	(22,998)
Balance, end of year		(172,541)	(181,151)	81,847
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
Balance, beginning of year	[1]	935,697	1,624,773	820,245
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	[1]	646,887	(1,101,760)	1,185,321
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	69,622	(72,795)	32,097
Other Comprehensive Income (Loss), Tax	[1]	(157,929)	339,889	(348,696)
Balance, end of year	[1]	1,355,033	935,697	1,624,773
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
Balance, beginning of year		(46,262)	(49,491)	(21,721)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax		(951)	(1,248)	(45,688)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		(5,822)	(6,203)	(3,148)
Other Comprehensive Income (Loss), Tax		(1,772)	(1,726)	14,770
Balance, end of year		$ (43,163)	$ (46,262)	$ (49,491)

[1] Includes cash flow hedges of $(2,496), $(29,397) and $(31,591) as of December 31, 2016, 2015 and 2014, respectively. See Note 5 for additional information on cash flow hedges.