CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
NET INCOME	$ 216,729	$ 84,735	$ 339,528	$ 208,404
OTHER COMPREHENSIVE INCOME:
Net reclassification adjustment for amounts recognized in net income as a component of net periodic benefit cost, net of income tax expense of $1,349 and $1,840 for the three months ended June 30, 2016 and 2015, and $2,698 and $3,648 for the six months ended June 30, 2016 and 2015, respectively	2,515	3,413	5,030	6,799
COMPREHENSIVE INCOME (LOSS)	$ 219,244	$ 88,148	$ 344,558	$ 215,203