Accounts Receivable, Net Of Allowance (Schedule Of Accounts Receivable) (Detail) (USD $)	Sep. 30, 2012	Dec. 31, 2011
Receivables [Abstract]
Contract billings	$ 486,200,000	$ 389,800,000
Retainage	105,500,000	41,700,000
Costs and earnings in excess of billings	289,000,000	228,700,000
Accounts receivable, gross	880,700,000	660,200,000
Less allowance for doubtful accounts	(7,600,000)	(7,600,000)
Accounts receivable, net	$ 873,102,000	$ 652,553,000