Accounts Receivable, Net Of Allowance (Schedule Of Accounts Receivable) (Detail) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Receivables [Abstract]
Contract billings	$ 468,400,000	$ 522,100,000
Retainage	111,000,000	113,500,000
Costs and earnings in excess of billings	337,800,000	252,800,000
Accounts receivable, gross	917,200,000	888,300,000
Less allowance for doubtful accounts	(14,700,000)	(11,200,000)
Accounts receivable, net	$ 902,426,000	$ 877,131,000