Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenue	$ 3,062,754	$ 3,659,624	$ 3,287,019
Cost of services and products	2,457,325	2,800,423	2,521,483
Gross Margin	605,429	859,201	765,536
Selling, general and administrative expense	231,619	230,871	220,420
Income from Operations	373,810	628,330	545,116
Interest income	607	293	554
Interest expense, net of amounts capitalized	(25,050)	(4,708)	(2,194)
Equity earnings of unconsolidated affiliates	2,230	(51)	133
Other income (expense), net	(15,336)	(387)	(1,273)
Income before Income Taxes	336,261	623,477	542,336
Provision for income taxes	105,250	195,148	170,836
Net Income	$ 231,011	$ 428,329	$ 371,500
Cash Dividends declared per Share	$ 1.08	$ 1.03	$ 0.84
Basic Earnings per Share	$ 2.35	$ 4.02	$ 3.43
Weighted Average Number of Shares Outstanding, Basic	98,417	106,593	108,158
Diluted Earnings per Share	$ 2.34	$ 4.00	$ 3.42
Weighted Average Number of Shares Outstanding, Diluted	98,808	107,091	108,731