Statements of Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended						3 Months Ended							3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 Unrealized Investment Gains (Losses) [Member]		Mar. 31, 2012 Unrealized Investment Gains (Losses) [Member]	Dec. 31, 2011 Unrealized Investment Gains (Losses) [Member]	Mar. 31, 2013 Currency Translation Adjustments [Member]	Mar. 31, 2012 Currency Translation Adjustments [Member]	Mar. 31, 2013 Net Pension Asset [Member]		Mar. 31, 2012 Net Pension Asset [Member]	Mar. 31, 2013 Accumulated Other Comprehensive Income (Loss) [Member]	Mar. 31, 2012 Accumulated Other Comprehensive Income (Loss) [Member]	Mar. 31, 2013 Noncontrolling Interest [Member]	Mar. 31, 2012 Noncontrolling Interest [Member]
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax, Portion Attributable to Noncontrolling Interest			$ (20,075)	[1]
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax, Portion Attributable to Noncontrolling Interest							0
Beginning of period	4,335,466		517,658		452,420	430,419	(36,676)	(61,239)	(15,351)		(14,329)	465,631	393,259	29,249	7,526
Other comprehensive income (loss) before reclassifications			20,989				(46,623)					(25,634)
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, Net of Tax									0
Amounts reclassified from AOCI			(13,179)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax							0
Amounts reclassified from AOCI	1,814	824							1,814		824	(11,365)
Other comprehensive income (loss)	(36,999)	38,431	7,810				(46,623)		1,814			(36,999)		40	23
Unrealized investment gain related to non-controlling interest	7,810	22,024	(40)				0		0
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Recognized in Net Periodic Benefit Cost, before Tax			12,015						2,792	[2]		(17,283)
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent												(31,816)
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax			6,896	[3]
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Noncontrolling Interest							0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Tax, Portion Attributable to Noncontrolling Interest			(4,205)						(978)	[3]		5,918
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent, Available-for-sale Securities												(5,183)
Other Comprehensive Income (Loss), Tax							0
Change in unrealized foreign exchange gains (losses)	(46,623)	15,583					(46,623)	15,583
End of period	4,410,630		525,428		452,420	430,419	(83,299)	(45,656)	(13,537)		(13,505)	428,592	393,259	32,089	8,539
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Income (Loss), Tax, Portion Attributable to Noncontrolling Interest, Available-for-sale Securities												$ (40)

[1] Net investment gains in the consolidated statements of operations.

[2] Other operating costs and expenses in the consolidated statements of operations.

[3] Income tax expense in the consolidated statements of operations.