Accumulated Other Comprehensive Income - Details about AOCI components (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net realized and unrealized gains (losses) on derivative instruments	$ 29,886		$ 7,798		$ 5,221
Operating Expenses	(1,341,315)		(1,213,178)		(1,173,955)
Exchange gains (losses) before tax	37,568		28,243		(10,545)
Amounts reclassified from AOCI	(128,094)		(85,692)		(9,036)
Provision for income tax	(96,897)		(77,505)		(34,028)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI	(128,094)		(85,692)
Provision for income tax	(1,974)		5,171
Total amount reclassified from AOCI, net of tax	(130,068)		(80,521)
Unrealized Gains (Losses) on Investments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains (losses) on investments sold	(175,639)		(130,236)
OTTI on investments	54,095		10,266
Amounts reclassified from AOCI	(143,330)	[1]	(119,970)	[1]	(81,678)	[1]
Provision for income tax	(1,593)		5,183
Total amount reclassified from AOCI, net of tax	(144,923)		(114,787)
OTTI Losses Recognized in AOCI
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI	14,082		32,193		67,580
OTTI Losses Recognized in AOCI | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains (losses) on investments sold	11,848		26,160
OTTI on investments	2,234		6,033
Amounts reclassified from AOCI	14,082		32,193
Provision for income tax	(175)		(12)
Total amount reclassified from AOCI, net of tax	13,907		32,181
Foreign Currency Translation Adjustments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI	87		206		350
Foreign Currency Translation Adjustments | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI	87		206
Provision for income tax	0		0
Total amount reclassified from AOCI, net of tax	87		206
Underfunded Pension Liability
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI	812		1,440		4,273
Underfunded Pension Liability | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Operating Expenses	812		1,440
Provision for income tax	(206)		0
Total amount reclassified from AOCI, net of tax	606		1,440
Cash Flow Hedge
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI	255		439		439
Cash Flow Hedge | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI	255		439
Provision for income tax	0		0
Total amount reclassified from AOCI, net of tax	255		439
Life Funds Withheld Assets [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains (losses) on investments sold	5,067		0		0
OTTI on investments	(20,587)		0		0
Net realized and unrealized gains (losses) on derivative instruments	(488,222)		0		0
Life Funds Withheld Assets [Member] | Unrealized Gains (Losses) on Investments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net realized and unrealized gains (losses) on derivative instruments	$ (21,786)		$ 0

[1] Included in these amounts is the impact of Shadow Adjustments. During the year ended December 31, 2013, the initial impact of $44.7 million was recorded. During the year ended December 31, 2014, additional net impacts of $400.5 million were recorded, resulting in a total cumulative net impact of Shadow Adjustments on future policy benefit reserves of $445.1 million at December 31, 2014.