The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Computation of Basic and Diluted Earnings per Common Share (Parenthetical) (Details) - shares		12 Months Ended
	Sep. 27, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
EPS Performance-based Restricted Stock Units
Computation Of Earnings Per Share [Line Items]
Contingently issuable shares excluded from calculation of weighted average common shares outstanding		46,000	54,000	59,000
Laser Quantum \| Restricted Stock
Computation Of Earnings Per Share [Line Items]
Contingently issuable shares excluded from calculation of weighted average common shares outstanding	213,219	213,000	213,000