Acquisitions - Composite Engineering, Inc. (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	0 Months Ended		3 Months Ended		6 Months Ended
	Jul. 02, 2012	May 14, 2012	Jun. 30, 2013	Jun. 24, 2012	Jun. 30, 2013	Jun. 24, 2012
Business Acquisition [Line Items]
Proceeds from the issuance of common stock					$ 0	$ 97.0
Business Combination, Acquisition Related Costs			(2.6)	1.5	(2.5)	2.4
Revenues			235.2	219.8	488.5	429.3
Operating income (loss)			8.9	7.4	20.3	16.5
Revolving credit facility
Business Acquisition [Line Items]
Outstanding borrowings			0		0
Composite Engineering, Inc.
Business Acquisition [Line Items]
Consideration transferred	164.0
Aggregate amount of cash paid	135.0
Number of shares given as part of purchase price	4.0
Purchase price per share	$ 5.94	$ 5.00
Common stock exchanged as consideration, value	23.8
Business Combination, Amount Placed in Escrow	10.7
Business Combination, Contingent Consideration Arrangement, Working Capital Adjustment	1.0
Consideration transferred, retirement of acquiree's debt	2.5
Consideration transferred, settlement of pre-existing accounts receivable	3.0
Additional tax liability incurred	1.6
Business Combination, Goodwill and Intangible Assets, Tax Deductible	140.6
Tax deductible goodwill, deduction realization period	15 years
Common stock issued for acquisitions	20.0	20.0
Gross proceeds from issuance of common stock		100.0
Proceeds from the issuance of common stock		97.0
Acquired accounts receivable, gross	9.3
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual			27.2		53.1
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual			3.6		6.8
Business Combination, Acquisition Related Costs				0.5		0.8
Composite Engineering, Inc. | Revolving credit facility
Business Acquisition [Line Items]
Outstanding borrowings	40.0
Composite Engineering, Inc. | Restricted Stock Units (RSUs) | Management
Business Acquisition [Line Items]
Number of shares issued as part of long-term employement agreements	2.0
Fair value of shares issued as part of long-term employement agreements	$ 11.9
Share-based compensation, period for recognition	4 years