Consolidated Statements Of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement of Comprehensive Income [Abstract]
Net income	$ 610,425	$ 385,555	$ 258,966
Pension and other post-retirement benefits liability
Pension and other post-retirement reserves adjustment (excluding amortization)	12,969	(4,301)	(6,620)
Amortization of benefits liability	2,712	2,340	1,985
Income tax provision on available-for-sale investments	(6,026)	753	1,820
Foreign currency translation adjustments	(1,607)	623	(407)
Available-for-sale investments
Unrealized holding gains on investments	256	14,582	1,848
Reclassification of net realized gain to net income	19	(16,429)	0
Income tax (provision) benefit on available-for-sale investment	99	(662)	663
Other comprehensive income (loss)	8,224	(1,770)	(2,037)
Comprehensive income	$ 618,649	$ 383,785	$ 256,929