Accumulated Other Comprehensive Income (Schedule of Reclassifications out of AOCI) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012	Sep. 30, 2013		Sep. 30, 2012
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Investment related gains (losses), net	$ (76,133)		$ 78,608	$ 76,792		$ 162,554
Investment income	369,366		396,781	1,238,731		1,066,055
Total before tax	201,695		201,479	405,764		598,134
Tax (expense) benefit	(63,740)		(57,004)	(131,886)		(189,230)
Net income	137,955		144,475	273,878		408,904
Unrealized Appreciation Depreciation Of Investments [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Total before tax	(13,047)			(3,515)
Tax (expense) benefit	5,009			1,988
Net income	(8,038)			(1,527)
Unrealized Appreciation Depreciation Of Investments [Member] | Unrealized Gains Losses On Available For Sale Securities [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Investment related gains (losses), net	(12,736)			11,122
Unrealized Appreciation Depreciation Of Investments [Member] | Gains Losses On Qualifying Cash Flow Hedging Instruments [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Investment income	291			796
Unrealized Appreciation Depreciation Of Investments [Member] | DAC Attributed To Unrealized Gains Losses [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Deferred policy acquisition costs attributed to unrealized gains and losses	(602)	[1]		(15,433)	[1]
Amortization Of Unrealized Pension And Postretirement Benefits [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Total before tax	(1,239)			(3,537)
Tax (expense) benefit	434			1,238
Net income	(805)			(2,299)
Amounts Reclassified From AOCI [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net income	(8,843)			(3,826)
Prior Service Cost [Member] | Amortization Of Unrealized Pension And Postretirement Benefits [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Prior service cost	(152)	[2]		(459)	[2]
Actuarial Gains Losses [Member] | Amortization Of Unrealized Pension And Postretirement Benefits [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Actuarial gains/(losses)	$ (1,087)	[2]		$ (3,078)	[2]

[1] This AOCI component is included in the computation of the deferred policy acquisition cost. See Note 8 – “Deferred Policy Acquisition Costs” of the 2012 Annual Report for additional details.

[2] These AOCI components are included in the computation of the net periodic pension cost. See Note 9 – “Employee Benefit Plans” for additional details.