Comprehensive Income (Balance of and Changes in Each Component of AOCI) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
Balance, beginning of year	$ 1,005,607		$ 2,108,902		$ 1,618,153
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(125,236)		(60,392)		37,680
Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	827,608	[1]	(1,063,377)	[1]	451,905	[1]
Accumulated Other Comprehensive Income (Loss), Other than Temporary Impairment, Not Credit Loss, Net of Tax, Available-for-sale, Debt Securities	1,698		2,896		6,434
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Loss, Net of Tax, Portion Attributable to Parent, Available-for-sale Securities	(1,698)		(2,896)		(6,434)
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax	(29,836)		11,577		(5,270)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(22,712)		6,001
Balance, end of year	1,657,129		1,005,607		2,108,902
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
Balance, beginning of year	207,083		267,475		229,795
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(125,236)		(60,392)		37,680
Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	0	[1]	0	[1]	0	[1]
Accumulated Other Comprehensive Income (Loss), Other than Temporary Impairment, Not Credit Loss, Net of Tax, Available-for-sale, Debt Securities	0		0		0
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax	0		0		0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0		0
Balance, end of year	81,847		207,083		267,475
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
Balance, beginning of year	820,245		1,877,657		1,419,318
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	0		0		0
Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	827,608	[1]	(1,063,377)	[1]	451,905	[1]
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax	0		0		0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	24,778		3,069
Balance, end of year	1,624,773		820,245		1,877,657
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
Balance, beginning of year	(21,721)		(36,230)		(30,960)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	0		0		0
Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	0	[1]	0	[1]	0	[1]
Accumulated Other Comprehensive Income (Loss), Other than Temporary Impairment, Not Credit Loss, Net of Tax, Available-for-sale, Debt Securities	0		0		0
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax	(29,836)		11,577		(5,270)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(2,066)		2,932
Balance, end of year	$ (49,491)		$ (21,721)		$ (36,230)

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