Commitments And Contingencies (Details) (USD $)	6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Jan. 31, 2011
Letters of credit outstanding	$ 33,447,000
Letter of credit remaining borrowing capacity	141,553,000
Senior notes interest rate	7.375%		7.375%
Outstanding performance bonds	269,419,000
Revenue value remaining from outstanding performance bonds	147,080,000
Senior Notes	250,000,000	250,000,000	250,000,000
Asbestos related personal lawsuit injury	251
Actual cases	40
Dismissal cases	3
Cases pending	37
Maximum [Member]
Bids bond range	10,000,000
Judgement	13,272,000
Minimum [Member]
Bids bond range	1,000,000
Judgement	11,736,000
Foreign Line of Credit [Member]
Letters of credit outstanding	11,725,000
Letters of credit , maximum borrowing capacity	$ 24,000,000