Fair Value Measurements and Disclosures (Tables)

6 Months Ended

Jun. 25, 2016

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:

	June 25, 2016								December 26, 2015
	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	$	14,381	$	—	$	—	$	14,381	$	590	$	—	$	—	$	590
Commercial paper and corporate debt    securities		—		—		—		—		—		4,568		—		4,568
Total cash equivalents	$	14,381	$	—	$	—	$	14,381	$	590	$	4,568	$	—	$	5,158
Marketable securities:
U.S. Treasury, U.S. Government and U.S.    Government agency debt securities		—		23,937		—		23,937		4,401		20,164		—		24,565
Commercial paper, municipal securities    and corporate debt securities		—		12,015		—		12,015		—		20,366		—		20,366
Total marketable securities	$	—	$	35,952	$	—	$	35,952	$	4,401	$	40,530	$	—	$	44,931
Total(1)	$	14,381	$	35,952	$	—	$	50,333	$	4,991	$	45,098	$	—	$	50,089
Liabilities:
Contingent consideration payable	$	—	$	—	$	1,270	$	1,270	$	—	$	—	$	1,490	$	1,490

⁽¹⁾ Excludes $45.7 million and $33.0 million held in operating accounts as of June 25, 2016 and December 26, 2015, respectively.

Fair value measurement on recurring basis, unobservable input reconciliation

Changes in Level 3 liabilities	(in thousands)
Fair value at December 26, 2015	$	1,490
Payments made to Zygo Corporation		(315	)
Change in fair value included in earnings		95
Fair value at June 25, 2016	$	1,270

Outstanding derivative instruments

The following table summarizes the Company’s outstanding derivative instruments on a gross basis as of June 25, 2016 :

	Notional Principal
	(in millions)
Undesignated Hedges:
Forward Foreign Currency Contracts	$	16.5