Legal Settlement	12 Months Ended
Dec. 31, 2011
Legal Settlement [Abstract]
Legal Settlement	Legal Settlement In August 2005, KLA-Tencor Corporation (“KLA”) filed a complaint against the Company in the United States District Court for the Northern District of California (the “California District Court”). The complaint alleged that certain of Nanometrics' products infringe two of KLA's patents. In January 2006, KLA added a third patent to its complaint. In August 2011, the Company filed a complaint against KLA in the United States District Court for the District of Delaware. The complaint alleged that several of KLA's overlay metrology products infringe two of the Company's patents. On January 13, 2012, the Company entered into a settlement and limited patent cross license agreement with KLA to resolve all existing patent litigation between the parties. Pursuant to the settlement agreement, the Company agreed to make a one-time payment of $2.5 million to KLA. The settlement additionally included other features including limited cross-licenses of the patents that were subject to the litigation. The Company determined the principal benefit of the settlement was the economic benefit of avoiding litigation expenses and that the value attributable to the other settlement features was de minimus. As a result, the Company recorded a $2.5 million charge to legal settlement in operating expense in the fourth quarter of fiscal 2011.

Legal Settlement

In August 2005, KLA-Tencor Corporation (“KLA”) filed a complaint against the Company in the United States District Court for the Northern District of California (the “California District Court”). The complaint alleged that certain of Nanometrics' products infringe two of KLA's patents. In January 2006, KLA added a third patent to its complaint. In August 2011, the Company filed a complaint against KLA in the United States District Court for the District of Delaware. The complaint alleged that several of KLA's overlay metrology products infringe two of the Company's patents. On January 13, 2012, the Company entered into a settlement and limited patent cross license agreement with KLA to resolve all existing patent litigation between the parties. Pursuant to the settlement agreement, the Company agreed to make a one-time payment of $2.5 million to KLA. The settlement additionally included other features including limited cross-licenses of the patents that were subject to the litigation. The Company determined the principal benefit of the settlement was the economic benefit of avoiding litigation expenses and that the value attributable to the other settlement features was de minimus. As a result, the Company recorded a $2.5 million charge to legal settlement in operating expense in the fourth quarter of fiscal 2011.