CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Comprehensive income:
Net income	$ 368,582	$ 364,752	$ 824,967	$ 798,179
Pension and retiree medical benefits:
Amortization of losses included in net periodic benefit cost, net of tax of $567, $686, $1,666 and $3,918, respectively	847	1,179	2,575	1,675
Derivative instruments:
Net fair value (decrease) increase, net of tax of $(27), $14, $(22), and $(2), respectively	(42)	22	(34)	(9)
Reclassification of losses to net income, net of tax of $393, $266, $1,115 and $2,145, respectively	558	539	1,693	928
Total derivative instruments, net of tax	516	561	1,659	919
Marketable securities:
Net fair value increase, net of tax of $1, $73, $26 and $56, respectively	2	115	40	79
Other comprehensive income	1,365	1,855	4,274	2,673
Comprehensive income	$ 369,947	$ 366,607	$ 829,241	$ 800,852