Recent Accounting Pronouncements	12 Months Ended
Dec. 30, 2017
Accounting Changes And Error Corrections [Abstract]
Recent Accounting Pronouncements	Note 2. Recent Accounting Pronouncements Accounting Standards Adopted In March 2016, the FASB issued an accounting standard update that simplifies several aspects of the accounting for share-based payment award transactions, including income tax consequences, classification of awards as equity or liability, and classification on the statement of cash flows. The new standard requires adoption of certain amendments relevant to the Company to be applied using a modified retrospective transition method by means of cumulative effect adjustment to retained earnings as of the beginning of the fiscal year 2017. The new standard permits entities to make an accounting policy election related to how forfeitures will impact the recognition of compensation cost for stock-based compensation. The Company has elected to account for forfeitures as they occur and adopted this change on a modified retrospective basis. The cumulative effect of this change resulted in a $0.1 million increase to accumulated deficit as of January 1, 2017. Furthermore, the standard requires excess tax benefits and tax deficiencies to be recorded in the income statement when the awards vest or are settled rather than paid-in capital. The Company recorded the cumulative effect of this change as a $1.2 million reduction to accumulated deficit in the first quarter of fiscal 2017 to reflect the recognition of excess tax benefits in prior years, with a corresponding adjustment to deferred tax assets and long-term tax liabilities. The Company adopted the guidance related to the recognition of excess tax benefits and deficiencies as income tax expense or benefit on a modified retrospective basis. In addition, the Company elected to report cash flows related to excess tax benefits on a prospective basis. The presentation requirements for cash flows related to employee taxes paid for withheld shares had no impact to the Company’s statement of cash flows since such cash flows have historically been presented as a financing activity. In July 2015, the FASB issued an accounting standard update which simplifies the measurement of inventory by requiring inventory to be measured at the lower of cost and net realizable value. The new standard applies only to inventories for which cost is determined by methods other than last-in-first-out and the retail inventory method. Effective in the first quarter of fiscal 2017, the Company adopted this guidance. The adoption of this guidance did not have a significant impact on the Company’s consolidated financial condition and results of operation. Accounting Standards Not Yet Adopted In January 2017, the Financial Accounting Standards Board (the "FASB") issued an accounting standard update which simplifies the subsequent measurement of goodwill and removes step 2 from the goodwill impairment test. Instead, an entity should record an impairment charge based on excess of a reporting unit’s carrying amount over its fair value. The standard is effective for public companies for fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The adoption of this guidance is not expected to have a significant impact on the Company’s consolidated financial condition and results of operations. In October 2016, the FASB issued an accounting standard update which requires the recognition of the income tax consequences of an intra-entity transfer of an asset, other than inventory, when the transfer occurs. This standard will be effective for annual reporting periods beginning after December 15, 2017, including interim reporting period within those annual periods. Early adoption is permitted. This standard update is required to be adopted using the modified retrospective approach, with a cumulative catch-up adjustment to retained earnings in the period of adoption. The Company is currently evaluating the impact of adopting this standard on its consolidated financial condition and results of operations. In August 2016, the FASB issued an accounting standard which addresses eight specific cash flow classification issues. This update is effective for public companies for fiscal years beginning after December 15, 2017 and interim periods within those fiscal years. Early adoption is permitted, including in an interim period. If early adopted in an interim period, any adjustments should be reflected as of the beginning of the fiscal year that includes that interim period, and all the amendments must be adopted in the same period. The standard is to be applied through a retrospective transition method to each period presented. If it is impracticable to apply retrospectively for some of the issues, the amendments for those issues would be applied prospectively as of the earliest date practicable. The adoption of this guidance is not expected to have a significant impact on the Company’s consolidated statement of cash flows. In June 2016, the FASB issued an accounting standard which requires measurement and timely recognition of expected credit losses for financial assets. The update is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted as of the fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. The standard is to be applied through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. The Company is currently evaluating the effect of this update on its consolidated financial condition and results of operations. In February 2016, the FASB issued an accounting standard update which requires lessees to record a right-of-use asset and a corresponding lease liability on the balance sheet (with the exception of short-term leases). For lessees, leases will continue to be classified as either operating or financing in the income statement. The standard is effective for public companies for annual reporting periods beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. This standard is required to be applied with a modified retrospective transition approach. The Company generally does not finance purchases of equipment or other capital, but does lease some equipment and facilities. The Company is currently evaluating the impact of this standard on its consolidated financial statements and related disclosures but anticipates most its existing operating lease commitments will be recognized as operating lease liabilities and right-of-use assets. In May 2014, the FASB issued an accounting standard update which requires an entity to recognize the amount of revenue to which it expects to be entitled to for transferring promised goods or services to customers. The updated standard replaces most existing revenue recognition guidance in U.S. GAAP when it becomes effective and permits the use of either the retrospective or cumulative effect transition method (“modified retrospective” method). In August 2015, the FASB deferred for one year the effective date of the new revenue standard, with early adoption permitted but not earlier than the original effective date. Consequently, the new standard will be effective for the Company on December 31, 2017 and the Company has determined it will not adopt early. Based on the Company’s assessment, the Company will adopt the new guidance in the first quarter of fiscal 2018 by using the modified retrospective method of transition. While the Company is concluding its assessment of the impact of the new standard, the Company believes that the timing of revenue recognition for certain systems and performance obligations, will generally occur earlier than under current revenue recognition guidance. Under current U.S. GAAP, revenue for certain systems or performance obligations is delayed until formal customer sign-off has occurred and/or contractual obligations have been met, whereas under the new standard, revenue should be recorded when transfer of control has occurred, which is normally upon shipment. While the Company expects revenue related to these arrangements to remain unchanged in total, the nature of when control transfers may change the timing of revenue recognition. Nanometrics expects the full-year positive impact to the opening balance of retained earnings related to the adoption of the new standard to be in the range of $0.7 million to $1.2 million. This amount reflects the margin related to revenue deferred as of December 30, 2017, that will not be reported as revenue in fiscal 2018. The amount of this revenue is estimated to be between $1.5 million and $2.5 million. This amount will also be reflected as a reduction to the beginning backlog of the first quarter of fiscal 2018. This amount is comprised of goods shipped in fiscal 2017 but deferred due to either lack of customer acceptance or failure of the customer to meet certain contractual commitments. Under the new standard, the Company has determined that transfer of control occurs at the time of shipment for these items and that the deferral of revenue associated with the unbilled amount is no longer appropriate per the new standard. Additionally, the Company believes the adoption of the new standard will not result in a different set of performance obligations, when compared to current GAAP. The Company further believes that required changes to its current business processes and IT systems, to comply with the new standard, will be minor in nature. Other aspects of the standard, including the capitalization of costs related to the acquisition and/or fulfillment of the Company’s contracts are still being evaluated, but the Company believes impacts are immaterial. The Company is concluding its evaluation of the impact of the new standard on the Company’s contracts with customers and will continue to monitor industry activities and other guidance provided by the accounting profession and regulators and adjust its approach and implementation plans as required.

Note 2. Recent Accounting Pronouncements

Accounting Standards Adopted

In March 2016, the FASB issued an accounting standard update that simplifies several aspects of the accounting for share-based payment award transactions, including income tax consequences, classification of awards as equity or liability, and classification on the statement of cash flows. The new standard requires adoption of certain amendments relevant to the Company to be applied using a modified retrospective transition method by means of cumulative effect adjustment to retained earnings as of the beginning of the fiscal year 2017.

The new standard permits entities to make an accounting policy election related to how forfeitures will impact the recognition of compensation cost for stock-based compensation. The Company has elected to account for forfeitures as they occur and adopted this change on a modified retrospective basis. The cumulative effect of this change resulted in a $0.1 million increase to accumulated deficit as of January 1, 2017.

Furthermore, the standard requires excess tax benefits and tax deficiencies to be recorded in the income statement when the awards vest or are settled rather than paid-in capital. The Company recorded the cumulative effect of this change as a $1.2 million reduction to accumulated deficit in the first quarter of fiscal 2017 to reflect the recognition of excess tax benefits in prior years, with a corresponding adjustment to deferred tax assets and long-term tax liabilities. The Company adopted the guidance related to the recognition of excess tax benefits and deficiencies as income tax expense or benefit on a modified retrospective basis. In addition, the Company elected to report cash flows related to excess tax benefits on a prospective basis. The presentation requirements for cash flows related to employee taxes paid for withheld shares had no impact to the Company’s statement of cash flows since such cash flows have historically been presented as a financing activity.

In July 2015, the FASB issued an accounting standard update which simplifies the measurement of inventory by requiring inventory to be measured at the lower of cost and net realizable value. The new standard applies only to inventories for which cost is determined by methods other than last-in-first-out and the retail inventory method. Effective in the first quarter of fiscal 2017, the Company adopted this guidance. The adoption of this guidance did not have a significant impact on the Company’s consolidated financial condition and results of operation.

Accounting Standards Not Yet Adopted

In January 2017, the Financial Accounting Standards Board (the "FASB") issued an accounting standard update which simplifies the subsequent measurement of goodwill and removes step 2 from the goodwill impairment test. Instead, an entity should record an impairment charge based on excess of a reporting unit’s carrying amount over its fair value. The standard is effective for public companies for fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The adoption of this guidance is not expected to have a significant impact on the Company’s consolidated financial condition and results of operations.

In October 2016, the FASB issued an accounting standard update which requires the recognition of the income tax consequences of an intra-entity transfer of an asset, other than inventory, when the transfer occurs. This standard will be effective for annual reporting periods beginning after December 15, 2017, including interim reporting period within those annual periods. Early adoption is permitted. This standard update is required to be adopted using the modified retrospective approach, with a cumulative catch-up adjustment to retained earnings in the period of adoption. The Company is currently evaluating the impact of adopting this standard on its consolidated financial condition and results of operations.

In August 2016, the FASB issued an accounting standard which addresses eight specific cash flow classification issues. This update is effective for public companies for fiscal years beginning after December 15, 2017 and interim periods within those fiscal years. Early adoption is permitted, including in an interim period. If early adopted in an interim period, any adjustments should be reflected as of the beginning of the fiscal year that includes that interim period, and all the amendments must be adopted in the same period. The standard is to be applied through a retrospective transition method to each period presented. If it is impracticable to apply retrospectively for some of the issues, the amendments for those issues would be applied prospectively as of the earliest date practicable. The adoption of this guidance is not expected to have a significant impact on the Company’s consolidated statement of cash flows.

In June 2016, the FASB issued an accounting standard which requires measurement and timely recognition of expected credit losses for financial assets. The update is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted as of the fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. The standard is to be applied through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. The Company is currently evaluating the effect of this update on its consolidated financial condition and results of operations.

In February 2016, the FASB issued an accounting standard update which requires lessees to record a right-of-use asset and a corresponding lease liability on the balance sheet (with the exception of short-term leases). For lessees, leases will continue to be classified as either operating or financing in the income statement. The standard is effective for public companies for annual reporting periods beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. This standard is required to be applied with a modified retrospective transition approach. The Company generally does not finance purchases of equipment or other capital, but does lease some equipment and facilities. The Company is currently evaluating the impact of this standard on its consolidated financial statements and related disclosures but anticipates most its existing operating lease commitments will be recognized as operating lease liabilities and right-of-use assets.

In May 2014, the FASB issued an accounting standard update which requires an entity to recognize the amount of revenue to which it expects to be entitled to for transferring promised goods or services to customers. The updated standard replaces most existing revenue recognition guidance in U.S. GAAP when it becomes effective and permits the use of either the retrospective or cumulative effect transition method (“modified retrospective” method). In August 2015, the FASB deferred for one year the effective date of the new revenue standard, with early adoption permitted but not earlier than the original effective date. Consequently, the new standard will be effective for the Company on December 31, 2017 and the Company has determined it will not adopt early.

Based on the Company’s assessment, the Company will adopt the new guidance in the first quarter of fiscal 2018 by using the modified retrospective method of transition. While the Company is concluding its assessment of the impact of the new standard, the Company believes that the timing of revenue recognition for certain systems and performance obligations, will generally occur earlier than under current revenue recognition guidance. Under current U.S. GAAP, revenue for certain systems or performance obligations is delayed until formal customer sign-off has occurred and/or contractual obligations have been met, whereas under the new standard, revenue should be recorded when transfer of control has occurred, which is normally upon shipment. While the Company expects revenue related to these arrangements to remain unchanged in total, the nature of when control transfers may change the timing of revenue recognition. Nanometrics expects the full-year positive impact to the opening balance of retained earnings related to the adoption of the new standard to be in the range of $0.7 million to $1.2 million. This amount reflects the margin related to revenue deferred as of December 30, 2017, that will not be reported as revenue in fiscal 2018. The amount of this revenue is estimated to be between $1.5 million and $2.5 million. This amount will also be reflected as a reduction to the beginning backlog of the first quarter of fiscal 2018. This amount is comprised of goods shipped in fiscal 2017 but deferred due to either lack of customer acceptance or failure of the customer to meet certain contractual commitments. Under the new standard, the Company has determined that transfer of control occurs at the time of shipment for these items and that the deferral of revenue associated with the unbilled amount is no longer appropriate per the new standard. Additionally, the Company believes the adoption of the new standard will not result in a different set of performance obligations, when compared to current GAAP. The Company further believes that required changes to its current business processes and IT systems, to comply with the new standard, will be minor in nature. Other aspects of the standard, including the capitalization of costs related to the acquisition and/or fulfillment of the Company’s contracts are still being evaluated, but the Company believes impacts are immaterial. The Company is concluding its evaluation of the impact of the new standard on the Company’s contracts with customers and will continue to monitor industry activities and other guidance provided by the accounting profession and regulators and adjust its approach and implementation plans as required.