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

12 Months Ended

Dec. 31, 2016

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,
	2016			2015
Contract billings	$	564.2		$	437.3
Retainage	268.6			148.8
Costs and earnings in excess of billings	331.6			332.7
Accounts receivable, gross	$	1,164.4		$	918.8
Less allowance for doubtful accounts	(8.4		)	(7.7		)
Accounts receivable, net	$	1,156.0		$	911.1

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,
	2016			2015
Allowance for doubtful accounts at beginning of year	$	7.7		$	13.9
Provision for doubtful accounts	2.9			2.1
Amounts charged against the allowance	(2.2		)	(8.3		)
Allowance for doubtful accounts at end of year	$	8.4		$	7.7