Condensed Consolidating Financial Statements - Balance Sheet (Details) - USD ($)	Jun. 28, 2015	Dec. 28, 2014	Jun. 29, 2014	May. 31, 2014	Dec. 29, 2013
Condensed Financial Statements, Captions [Line Items]
Principal	$ 669,200,000	$ 669,800,000
Current assets:
Cash and cash equivalents	22,200,000	33,500,000	$ 24,000,000		$ 54,200,000
Accounts receivable, net	204,500,000	217,500,000
Amounts due from affiliated companies	0	0
Inventoried costs	49,500,000	47,400,000
Other current assets	23,300,000	22,700,000
Current assets of discontinued operations	53,700,000	53,800,000
Total current assets	353,200,000	374,900,000
Property, plant and equipment, net	60,900,000	61,600,000
Goodwill	483,400,000	483,400,000
Intangible assets, net	42,200,000	49,500,000
Investment in subsidiaries	0	0
Other assets	28,600,000	32,400,000
Non-current assets of discontinued operations	134,300,000	137,000,000
Total assets	1,102,600,000	1,138,800,000
Current liabilities:
Accounts payable	46,200,000	44,600,000
Accrued expenses	33,900,000	38,000,000
Accrued compensation	34,100,000	41,100,000
Billings in excess of costs and earnings on uncompleted contracts	49,800,000	49,600,000
Deferred income tax liability	30,200,000	30,300,000
Amounts due to affiliated companies	0	0
Other current liabilities	5,600,000	7,900,000
Current liabilities of discontinued operations	16,100,000	14,600,000
Total current liabilities	215,900,000	226,100,000
Long-term debt, net of current portion	663,000,000	663,000,000
Other long-term liabilities	24,400,000	24,900,000
Non-current liabilities of discontinued operations	600,000	500,000
Total liabilities	903,900,000	914,500,000
Total stockholders' equity	198,700,000	224,300,000
Total liabilities and stockholders’ equity	$ 1,102,600,000	1,138,800,000
Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Ownership percentage	100.00%
Parent Company
Current assets:
Cash and cash equivalents	$ 15,400,000	28,700,000
Accounts receivable, net	0	0
Amounts due from affiliated companies	355,800,000	360,200,000
Inventoried costs	0	0
Other current assets	6,000,000	4,400,000
Current assets of discontinued operations	0	0
Total current assets	377,200,000	393,300,000
Property, plant and equipment, net	1,900,000	2,000,000
Goodwill	0	0
Intangible assets, net	0	0
Investment in subsidiaries	476,900,000	483,100,000
Other assets	27,000,000	27,800,000
Non-current assets of discontinued operations	0	0
Total assets	883,000,000	906,200,000
Current liabilities:
Accounts payable	4,900,000	3,100,000
Accrued expenses	7,200,000	6,300,000
Accrued compensation	3,800,000	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	500,000	500,000
Current liabilities of discontinued operations	600,000	700,000
Total current liabilities	17,000,000	15,800,000
Long-term debt, net of current portion	660,800,000	660,200,000
Other long-term liabilities	6,500,000	5,900,000
Non-current liabilities of discontinued operations	0	0
Total liabilities	684,300,000	681,900,000
Total stockholders' equity	198,700,000	224,300,000
Total liabilities and stockholders’ equity	883,000,000	906,200,000
Guarantors on a Combined Basis
Current assets:
Cash and cash equivalents	(1,900,000)	(5,500,000)
Accounts receivable, net	183,800,000	196,400,000
Amounts due from affiliated companies	0	0
Inventoried costs	30,800,000	32,200,000
Other current assets	13,300,000	15,500,000
Current assets of discontinued operations	49,500,000	49,800,000
Total current assets	275,500,000	288,400,000
Property, plant and equipment, net	51,900,000	52,000,000
Goodwill	442,600,000	442,600,000
Intangible assets, net	42,200,000	49,400,000
Investment in subsidiaries	55,200,000	48,100,000
Other assets	1,600,000	4,600,000
Non-current assets of discontinued operations	131,800,000	134,500,000
Total assets	1,000,800,000	1,019,600,000
Current liabilities:
Accounts payable	37,600,000	37,100,000
Accrued expenses	23,900,000	28,900,000
Accrued compensation	27,300,000	32,700,000
Billings in excess of costs and earnings on uncompleted contracts	45,600,000	45,700,000
Deferred income tax liability	30,200,000	30,300,000
Amounts due to affiliated companies	314,300,000	316,800,000
Other current liabilities	4,200,000	5,900,000
Current liabilities of discontinued operations	12,700,000	10,800,000
Total current liabilities	495,800,000	508,200,000
Long-term debt, net of current portion	0	0
Other long-term liabilities	15,800,000	16,100,000
Non-current liabilities of discontinued operations	300,000	200,000
Total liabilities	511,900,000	524,500,000
Total stockholders' equity	488,900,000	495,100,000
Total liabilities and stockholders’ equity	1,000,800,000	1,019,600,000
Non-Guarantors on a Combined Basis
Current assets:
Cash and cash equivalents	8,700,000	10,300,000
Accounts receivable, net	20,700,000	21,100,000
Amounts due from affiliated companies	0	0
Inventoried costs	18,700,000	15,200,000
Other current assets	4,000,000	2,800,000
Current assets of discontinued operations	4,200,000	4,000,000
Total current assets	56,300,000	53,400,000
Property, plant and equipment, net	7,100,000	7,600,000
Goodwill	40,800,000	40,800,000
Intangible assets, net	0	100,000
Investment in subsidiaries	0	0
Other assets	0	0
Non-current assets of discontinued operations	2,500,000	2,500,000
Total assets	106,700,000	104,400,000
Current liabilities:
Accounts payable	3,700,000	4,400,000
Accrued expenses	2,800,000	2,800,000
Accrued compensation	3,000,000	3,200,000
Billings in excess of costs and earnings on uncompleted contracts	4,200,000	3,900,000
Deferred income tax liability	0	0
Amounts due to affiliated companies	41,500,000	43,400,000
Other current liabilities	900,000	1,500,000
Current liabilities of discontinued operations	2,800,000	3,100,000
Total current liabilities	58,900,000	62,300,000
Long-term debt, net of current portion	2,200,000	2,800,000
Other long-term liabilities	2,100,000	2,900,000
Non-current liabilities of discontinued operations	300,000	300,000
Total liabilities	63,500,000	68,300,000
Total stockholders' equity	43,200,000	36,100,000
Total liabilities and stockholders’ equity	106,700,000	104,400,000
Eliminations
Current assets:
Cash and cash equivalents	0	0
Accounts receivable, net	0	0
Amounts due from affiliated companies	(355,800,000)	(360,200,000)
Inventoried costs	0	0
Other current assets	0	0
Current assets of discontinued operations	0	0
Total current assets	(355,800,000)	(360,200,000)
Property, plant and equipment, net	0	0
Goodwill	0	0
Intangible assets, net	0	0
Investment in subsidiaries	(532,100,000)	(531,200,000)
Other assets	0	0
Non-current assets of discontinued operations	0	0
Total assets	(887,900,000)	(891,400,000)
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	(355,800,000)	(360,200,000)
Other current liabilities	0	0
Current liabilities of discontinued operations	0	0
Total current liabilities	(355,800,000)	(360,200,000)
Long-term debt, net of current portion	0	0
Other long-term liabilities	0	0
Non-current liabilities of discontinued operations	0	0
Total liabilities	(355,800,000)	(360,200,000)
Total stockholders' equity	(532,100,000)	(531,200,000)
Total liabilities and stockholders’ equity	(887,900,000)	$ (891,400,000)
Senior notes | 7.00% Senior Notes due 2019
Condensed Financial Statements, Captions [Line Items]
Principal	$ 625,000,000			$ 625,000,000.0