Comprehensive Income (Loss) (Components Of Comprehensive Income (Loss) In The Consolidated Statements Of Operations) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Comprehensive Income (Loss) [Abstract]
Net income (loss)	$ 23,967	$ 155,985	$ 125,653	$ 214,724	$ (114,356)	$ 261	$ 8,807	$ (97,533)	$ 520,329	$ (202,821)	$ 265,397
URA(D) of investments - temporary									14,682	34,109	(81,731)
URA(D) of investments - non-credit OTTI									(236)	(188)	2,862
URA(D) on securities arising during period									14,446	33,921	(78,869)
Less: reclassification adjustment for realized losses (gains) included in net income (loss)									974	31,138	35,429
Total URA(D) on securities arising during period									15,420	65,059	(43,440)
Foreign currency translation adjustments									10,815	(4,316)	41,597
Pension adjustments									(10,732)	(45,310)	(2,792)
Total other comprehensive income (loss), before tax									15,504	15,434	(4,635)
Tax benefit (expense) on URA(D) of investments - temporary									(5,139)	(11,939)	28,606
Tax benefit (expense) on URA(D) of investments - non-credit OTTI									83	66	(1,002)
Tax benefit (expense) on URA(D) on securities arising durign the period									(5,056)	(11,873)	27,604
Less: reclassification of tax expense (benefit) on realized losses (gains) included in net income (loss)									(341)	(10,898)	(12,400)
Total tax benefit (expense) from URA(D) arising during the period									(5,397)	(22,771)	15,204
Tax benefit (expense) from foreign currency translation									(3,786)	1,511	(14,558)
Tax benefit (expense) on pension									3,756	15,858	977
Total income tax benefit (expense) related to items of other comprehensive income (loss):									(5,427)	(5,402)	1,623
Other comprehensive income (loss), net of tax:									10,077	10,032	(3,012)
COMPREHENSIVE INCOME (LOSS)									$ 530,406	$ (192,789)	$ 262,385