CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Jul. 01, 2017	Dec. 31, 2016	Jul. 02, 2016
Statement of Financial Position [Abstract]
Accumulated depreciation	$ 384,881	$ 345,907	$ 317,580
Preferred stock; par value (USD per share)	$ 0.01	$ 0.01	$ 0.01
Preferred stock; shares authorized	100,000	100,000	100,000
Preferred stock; issued	0	0	0
Preferred stock; outstanding	0	0	0
Common stock, voting; par value (USD per share)	$ 0.01	$ 0.01	$ 0.01
Common stock, voting; shares authorized	150,000,000	150,000,000	150,000,000
Common stock voting; shares issued	47,971,577	48,948,670	50,194,955
Common stock voting; shares outstanding	47,971,577	48,948,670	50,194,955

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.14)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Face amount or stated value per share of common stock.

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

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