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Financial Instruments (Details) - USD ($)	3 Months Ended		9 Months Ended
Financial Instruments (Details) - USD ($)	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016	Dec. 31, 2016
Derivative [Line Items]
Interest rate cap hedges recognized in other comprehensive income, net of tax	$ 28,000	$ 0	$ 271,000	$ 556,000
Other Current Assets
Derivative [Line Items]
Derivative asset	0		0		$ 0
Other Long Term Assets
Derivative [Line Items]
Derivative asset	122,000		122,000		553,000
Interest rate cap premiums
Derivative [Line Items]
Interest rate cap hedges recognized in other comprehensive income, net of tax	0
Gain (loss) on derivatives, net	0
Cash Flow Hedging \| Designated as Hedging Instrument \| Interest rate cap premiums \| Other Current Assets
Derivative [Line Items]
Derivative asset	0		0		0
Cash Flow Hedging \| Designated as Hedging Instrument \| Interest rate cap premiums \| Other Long Term Assets
Derivative [Line Items]
Derivative asset	$ 122,000		$ 122,000		$ 553,000