Consolidated Statements Of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Revenue	$ 2,192,663	$ 1,917,045	$ 1,822,081
Cost of services and products	1,683,904	1,450,725	1,384,355
Gross Margin	508,759	466,320	437,726
Selling, general and administrative expense	173,928	156,820	145,610
Income from Operations	334,831	309,500	292,116
Interest income	888	580	694
Interest expense, net of amounts capitalized	(1,096)	(6,010)	(7,781)
Equity earnings of unconsolidated affiliates	3,801	2,078	3,242
Other income (expense), net	(539)	(926)	1,504
Income before Income Taxes	337,885	305,222	289,775
Provision for income taxes	102,227	104,691	101,422
Net Income	$ 235,658	$ 200,531	$ 188,353
Cash Dividends declared per Share	$ 0.45	$ 0.00	$ 0.00
Basic Earnings per Share	$ 2.18	$ 1.83	$ 1.71
Diluted Earnings per Share	$ 2.16	$ 1.82	$ 1.70