Fair Value Measurements and Disclosures (Tables)

3 Months Ended

Mar. 28, 2015

Fair Value Disclosures [Abstract]

Assets and liabilities measurements at estimated fair value on recurring basis excluding accrued interest components

The following tables present the Company’s assets and liabilities measured at estimated fair value on a recurring basis, excluding accrued interest components, categorized in accordance with the fair value hierarchy (in thousands), as of the following dates:

	March 28, 2015								December 27, 2014
	Fair Value Measurements Using Input Types								Fair Value Measurements Using Input Types
	Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents:
Money market funds	$	909	$	—	$	—	$	909	$	610	$	—	$	—	$	610
Total cash equivalents	909		—		—		909		610		—		—		610
Marketable securities:
U.S. Treasury, U.S. Government and U.S. Government agency debt securities	2,499		21,554		—		24,053		2,497		20,537		—		23,034
Commercial paper, municipal securities and corporate debt securities	—		25,061		—		25,061		—		26,252		—		26,252
Total marketable securities	2,499		46,615		—		49,114		2,497		46,789		—		49,286
Total(1)	$	3,408	$	46,615	$	—	$	50,023	$	3,107	$	46,789	$	—	$	49,896
Liabilities:
Contingent consideration payable	$	—	$	—	$	2,208	$	2,208	$	—	$	—	$	2,397	$	2,397

⁽¹⁾ Excludes $27.0 million and $34.1 million held in operating accounts as of March 28, 2015 and December 27, 2014, respectively.

Fair value measurement on recurring basis, unobservable input reconciliation

Changes in Level 3 liabilities (in thousands)
Fair value at December 27, 2014	2,397
Payments made to Zygo Corporation	(224		)
Change in fair value included in earnings	35
Fair value at March 28, 2015	$	2,208