Fair Value Measurements and Disclosures (Tables)

6 Months Ended

Jun. 30, 2012

Fair Value Measurements and Disclosures [Abstract]

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

	June 30, 2012								December 31, 2011
	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	$	65,502	$	—	$	—	$	65,502	$	70,899	$	—	$	—	$	70,899
Commercial paper and corporate debt securities		—		1,117		—		1,117		—		—		—		—
Cash and Cash Equivalents		65,502		1,117		—		66,619		70,899		—		—		70,899
Marketable Securities:
U.S. Treasury, U.S. Government and U.S. Government agency debt securities		5,634		—		—		5,634		—		—		—		—
Commercial paper and corporate debt securities		—		8,123		—		8,123		—		—		—		—
Total		5,634		8,123		—		13,757		—		—		—		—
Total assets:	$	71,136	$	9,240	$	—	$	80,376	$	70,899	$	—	$	—	$	70,899
Liabilities:
Contingent consideration payable	$	—	$	—	$	2,642	$	2,642	$	—	$	—	$	3,194	$	3,194

Fair value measurement on recurring basis, unobservable input reconciliation

Changes in Level 3 liabilities
Fair value at December 31, 2011	$	3,194
Payments made to Zygo Corporation		(198	)
Change in fair value included in earnings		207
Adjustment to the purchase price allocation of royalty payments to RTM related to acquisition of Nanda Technologies GmbH		(561	)
Fair Value at June 30, 2012	$	2,642