Condensed Consolidating Financial Statements - Balance Sheet (Details) (USD $)	Mar. 29, 2015	Dec. 28, 2014	Mar. 30, 2014	Dec. 29, 2013	May 31, 2014
Condensed Financial Statements, Captions [Line Items]
Principal	$ 669,500,000	$ 669,800,000
Current assets:
Cash and cash equivalents	34,400,000	34,700,000	53,600,000	55,700,000
Accounts receivable, net	238,600,000	248,200,000
Amounts due from affiliated companies	0	0
Inventoried costs	72,100,000	68,000,000
Other current assets	21,100,000	24,000,000
Total current assets	366,200,000	374,900,000
Property, plant and equipment, net	81,500,000	82,600,000
Goodwill	596,400,000	596,400,000
Intangible assets, net	47,700,000	52,300,000
Investment in subsidiaries	0	0
Amounts due from affiliated companies	0	0
Other assets	30,800,000	32,600,000
Total assets	1,122,600,000	1,138,800,000
Current liabilities:
Accounts payable	42,500,000	48,400,000
Accrued expenses	48,000,000	39,800,000
Accrued compensation	39,200,000	46,400,000
Billings in excess of costs and earnings on uncompleted contracts	56,500,000	52,100,000
Deferred income tax liability	30,200,000	30,300,000
Amounts due to affiliated companies	0	0
Other current liabilities	6,600,000	9,100,000
Total current liabilities	223,000,000	226,100,000
Long-term debt, net of current portion	663,000,000	663,000,000
Amounts due to affiliated companies	0	0
Other long-term liabilities	25,100,000	25,400,000
Total liabilities	911,100,000	914,500,000
Total stockholders' equity	211,500,000	224,300,000
Total liabilities and stockholders’ equity	1,122,600,000	1,138,800,000
Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Ownership percentage	100.00%
Parent Company
Current assets:
Cash and cash equivalents	21,600,000	28,700,000
Accounts receivable, net	0	0
Amounts due from affiliated companies	347,100,000	341,900,000
Inventoried costs	0	0
Other current assets	2,900,000	4,400,000
Total current assets	371,600,000	375,000,000
Property, plant and equipment, net	1,900,000	2,000,000
Goodwill	0	0
Intangible assets, net	0	0
Investment in subsidiaries	499,400,000	498,300,000
Amounts due from affiliated companies	0	0
Other assets	27,400,000	27,800,000
Total assets	900,300,000	903,100,000
Current liabilities:
Accounts payable	3,500,000	3,100,000
Accrued expenses	17,400,000	6,300,000
Accrued compensation	3,300,000	5,200,000
Billings in excess of costs and earnings on uncompleted contracts	0	0
Deferred income tax liability	0	0
Amounts due to affiliated companies	0	0
Other current liabilities	600,000	1,000,000
Total current liabilities	24,800,000	15,600,000
Long-term debt, net of current portion	660,500,000	660,200,000
Amounts due to affiliated companies	0	0
Other long-term liabilities	3,500,000	3,000,000
Total liabilities	688,800,000	678,800,000
Total stockholders' equity	211,500,000	224,300,000
Total liabilities and stockholders’ equity	900,300,000	903,100,000
Guarantors on a Combined Basis
Current assets:
Cash and cash equivalents	400,000	(6,000,000)
Accounts receivable, net	209,700,000	217,700,000
Amounts due from affiliated companies	0	0
Inventoried costs	51,900,000	49,900,000
Other current assets	14,700,000	16,300,000
Total current assets	276,700,000	277,900,000
Property, plant and equipment, net	69,700,000	70,600,000
Goodwill	572,400,000	572,400,000
Intangible assets, net	47,700,000	52,200,000
Investment in subsidiaries	52,700,000	48,300,000
Amounts due from affiliated companies	3,200,000	3,200,000
Other assets	3,300,000	4,600,000
Total assets	1,025,700,000	1,029,200,000
Current liabilities:
Accounts payable	34,400,000	40,400,000
Accrued expenses	26,600,000	30,200,000
Accrued compensation	32,200,000	37,700,000
Billings in excess of costs and earnings on uncompleted contracts	52,000,000	47,000,000
Deferred income tax liability	30,300,000	30,300,000
Amounts due to affiliated companies	314,800,000	306,600,000
Other current liabilities	4,600,000	6,500,000
Total current liabilities	494,900,000	498,700,000
Long-term debt, net of current portion	0
Amounts due to affiliated companies	0	0
Other long-term liabilities	19,400,000	20,200,000
Total liabilities	514,300,000	518,900,000
Total stockholders' equity	511,400,000	510,300,000
Total liabilities and stockholders’ equity	1,025,700,000	1,029,200,000
Non-Guarantors on a Combined Basis
Current assets:
Cash and cash equivalents	12,400,000	12,000,000
Accounts receivable, net	28,900,000	30,500,000
Amounts due from affiliated companies	0	0
Inventoried costs	20,200,000	18,100,000
Other current assets	3,500,000	3,300,000
Total current assets	65,000,000	63,900,000
Property, plant and equipment, net	9,900,000	10,000,000
Goodwill	24,000,000	24,000,000
Intangible assets, net	0	100,000
Investment in subsidiaries	0	0
Amounts due from affiliated companies	0	0
Other assets	100,000	200,000
Total assets	99,000,000	98,200,000
Current liabilities:
Accounts payable	4,600,000	4,900,000
Accrued expenses	4,000,000	3,300,000
Accrued compensation	3,700,000	3,500,000
Billings in excess of costs and earnings on uncompleted contracts	4,500,000	5,100,000
Deferred income tax liability	(100,000)	0
Amounts due to affiliated companies	32,300,000	35,300,000
Other current liabilities	1,400,000	1,600,000
Total current liabilities	50,400,000	53,700,000
Long-term debt, net of current portion	2,500,000	2,800,000
Amounts due to affiliated companies	3,200,000	3,200,000
Other long-term liabilities	2,200,000	2,200,000
Total liabilities	58,300,000	61,900,000
Total stockholders' equity	40,700,000	36,300,000
Total liabilities and stockholders’ equity	99,000,000	98,200,000
Eliminations
Current assets:
Cash and cash equivalents	0	0
Accounts receivable, net	0	0
Amounts due from affiliated companies	(347,100,000)	(341,900,000)
Inventoried costs	0	0
Other current assets	0	0
Total current assets	(347,100,000)	(341,900,000)
Property, plant and equipment, net	0	0
Goodwill	0	0
Intangible assets, net	0	0
Investment in subsidiaries	(552,100,000)	(546,600,000)
Amounts due from affiliated companies	(3,200,000)	(3,200,000)
Other assets	0	0
Total assets	(902,400,000)	(891,700,000)
Current liabilities:
Accounts payable	0	0
Accrued expenses	0	0
Accrued compensation	0	0
Billings in excess of costs and earnings on uncompleted contracts	0	0
Deferred income tax liability	0	0
Amounts due to affiliated companies	(347,100,000)	(341,900,000)
Other current liabilities	0	0
Total current liabilities	(347,100,000)	(341,900,000)
Long-term debt, net of current portion	0	0
Amounts due to affiliated companies	(3,200,000)	(3,200,000)
Other long-term liabilities	0	0
Total liabilities	(350,300,000)	(345,100,000)
Total stockholders' equity	(552,100,000)	(546,600,000)
Total liabilities and stockholders’ equity	(902,400,000)	(891,700,000)
Senior notes | 7.00% Senior Notes due 2019
Condensed Financial Statements, Captions [Line Items]
Principal	$ 625,000,000				$ 625,000,000.0