Acquisitions - Composite Engineering, Inc. (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended			0 Months Ended		3 Months Ended		0 Months Ended
	Mar. 31, 2013	Mar. 25, 2012	Mar. 31, 2013 Revolving credit facility	Jul. 02, 2012 Composite Engineering, Inc.	May 14, 2012 Composite Engineering, Inc.	Mar. 31, 2013 Composite Engineering, Inc.	Jul. 02, 2012 Composite Engineering, Inc. Revolving credit facility	Jul. 02, 2012 Composite Engineering, Inc. Restricted Stock Units (RSUs) Management
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
Common stock issued for acquisitions				20.0	20.0
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
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
Gross proceeds from issuance of common stock					100.0
Proceeds from the issuance of common stock					97.0
Outstanding borrowings			0				40.0
Acquired accounts receivable, gross				9.3
Revenues	252.8	209.5				25.9
Operating income (loss)	$ 11.5	$ 9.1				$ 3.2