Consolidated Statements Of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenue	$ 2,782,604	$ 2,192,663	$ 1,917,045
Cost of services and products	2,154,746	1,683,904	1,450,725
Gross Margin	627,858	508,759	466,320
Selling, general and administrative expense	199,261	173,928	156,820
Income from Operations	428,597	334,831	309,500
Interest income	1,935	888	580
Interest expense, net of amounts capitalized	(4,218)	(1,096)	(6,010)
Equity earnings of unconsolidated affiliates	1,673	3,801	2,078
Other income (expense), net	(6,065)	(539)	(926)
Income before Income Taxes	421,922	337,885	305,222
Provision for income taxes	132,905	102,227	104,691
Net Income	$ 289,017	$ 235,658	$ 200,531
Cash Dividends declared per Share	$ 0.69	$ 0.45	$ 0.00
Basic Earnings per Share	$ 2.68	$ 2.18	$ 1.83
Diluted Earnings per Share	$ 2.66	$ 2.16	$ 1.82