Accounts Receivable, Net of Allowance (Tables) - Accounts Receivable [Member]

12 Months Ended

Dec. 31, 2014

Schedule of Accounts Receivable, Net of Allowance [Line Items]

Schedule of Accounts Receivable, Net of Allowance

The following table provides details of accounts receivable, net of allowance, as of the dates indicated (in millions):

	December 31,
	2014			2013
Contract billings	$	669.7		$	598.2
Retainage	162.2			159.3
Costs and earnings in excess of billings	485.6			392.9
Accounts receivable, gross	$	1,317.5		$	1,150.4
Less allowance for doubtful accounts	(13.9		)	(15.7		)
Accounts receivable, net	$	1,303.6		$	1,134.7

Schedule of Activity, Allowance for Doubtful Accounts

Activity in the allowance for doubtful accounts for the periods indicated is as follows (in millions):

	For the Years Ended December 31,
	2014			2013
Allowance for doubtful accounts at beginning of year	$	15.7		$	11.3
Provision for doubtful accounts	1.8			6.1
Amounts charged against the allowance	(3.6		)	(1.7		)
Allowance for doubtful accounts at end of year	$	13.9		$	15.7