Consolidated Statement of Comprehensive Income (Parenthetical) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Consolidated Statement of Comprehensive Income
Net actuarial (losses) and prior service cost and credits and amortization of net actuarial losses and prior service cost and credits, taxes	$ (276,076)	$ (391,528)	$ (70,389)
Unrealized (losses) gains on marketable equity securities, taxes	(4,079)	8,338	61
Net adjustments for derivative instruments designated as cash flow hedges, taxes	$ (29,417)	$ 19,857	$ 20,567