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	$ 252,576	$ 180,602	$ 736,841
Pension and other postretirement benefit adjustments, net of tax:
Prior service (cost) credit arising during the period, net of tax expense of ($1,255), $337, and $0, respectively	(2,330)	626	0
Net (loss) gain arising during the period, net of tax benefit of ($35,347), $8,340 and $43,017, respectively	65,645	(15,488)	(79,888)
Amortization of net loss, net of tax expense of $9,959, $11,986 and $7,611, respectively	18,495	22,259	14,135
Amortization of transition obligation, net of tax expense of $0, $166 and $297, respectively	0	308	552
Amortization of net loss, net of tax expense of $9,959, $11,986 and $7,611, respectively	(3,173)	(3,116)	(14,975)
OTHER COMPREHENSIVE INCOME	78,637	4,589	(80,176)
COMPREHENSIVE INCOME	$ 331,213	$ 185,191	$ 656,665