Acquisitions Acquisitions - Composite Engineering, Inc. (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	0 Months Ended	3 Months Ended		9 Months Ended				0 Months Ended		3 Months Ended		0 Months Ended
	Feb. 11, 2011	Sep. 30, 2012	Sep. 25, 2011	Sep. 30, 2012	Sep. 25, 2011	Dec. 25, 2011	Sep. 30, 2012 Revolving credit facility	Jul. 02, 2012 Composite Engineering, Inc.	May 14, 2012 Composite Engineering, Inc.	Sep. 30, 2012 Composite Engineering, Inc.	Jul. 02, 2012 Composite Engineering, Inc. Revolving credit facility	Jul. 02, 2012 Composite Engineering, Inc. Restricted Stock Units (RSUs) Management	Jul. 02, 2012 Composite Engineering, Inc. Escrow account
Business Acquisition [Line Items]
Consideration transferred								$ 163.5
Aggregate amount of cash paid								135.0
Contingent consideration, fair value		3.1		3.1		7.6							10.7
Common stock issued for acquisitions				4.0	10.4			4.0	20.0
Purchase price per share	$ 13.25							$ 5.94	$ 5.00
Common stock exchanged as consideration, value								23.8
Consideration transferred, retirement of acquiree's debt								2.5
Consideration transferred, settlement of pre-existing accounts receivable								3.0
Additional tax liability incurred								0.8
Tax deductible goodwill								101.0
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	64.8								100.0
Proceeds from the issuance of common stock	61.1			97.0	61.1				97.0
Outstanding borrowings							0				40.0
Acquired accounts receivable, gross								9.3
Revenues		276.3	206.6	705.6	500.5					34.7
Operating income (loss)		$ 14.1	$ 9.7	$ 30.6	$ 19.8					$ 1.7