Comprehensive Income (Components of Net Unrealized Appreciation Depreciation of Balances Carried at Fair Value) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Comprehensive Income Net Of Tax [Line Items]
Fixed maturity securities available-for-sale	$ 25,480,972		$ 21,474,136
Other invested assets	1,198,319		1,324,960
Deferred policy acquisition costs	3,342,575		3,517,796		3,619,274		3,543,925
Accumulated Other Comprehensive Income Loss Change In Component During Period	1,153,224		(1,524,866)		705,021
Change In Net Unrealized Appreciation Depreciation [Member]
Comprehensive Income Net Of Tax [Line Items]
Fixed maturity securities available-for-sale	1,171,996		(1,528,773)		713,778
Other invested assets	(14,292)	[1]	(12,274)	[1]	6,181	[1]
Effect On Unrealized Appreciation Depreciation [Member]
Comprehensive Income Net Of Tax [Line Items]
Deferred policy acquisition costs	$ (4,480)		$ 16,181		$ (14,938)

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