Note 1 - Summary of Significant Accounting Policies and Other Information	3 Months Ended
Apr. 01, 2017
Notes to Financial Statements
Significant Accounting Policies [Text Block]	1. Summary of Significant Accounting Policies and Other Information Nature of Operations Littelfuse, Inc. and subsidiaries (the “Company”) design, manufacture, and sell circuit protection devices for use in the automotive, electronics, and industrial markets throughout the world. The Company is one of the world’s leading suppliers of circuit protection products for the electronics, automotive, and industrial markets, with expanding platforms in sensors and power control components and modules. In addition to circuit protection products and solutions, the Company offers electronic reed switches and sensors, automotive sensors for comfort and safety systems and a comprehensive line of highly reliable electromechanical and electronic switch and control devices for commercial and specialty vehicles, as well as protection relays and power distribution centers for the safe control and distribution of electricity. The Company has a network of global engineering centers and labs that develop new products and product enhancements, provides customer application support and test products for safety, reliability, and regulatory compliance. The Company’s devices protect products in virtually every market that uses electrical energy, from consumer electronics to automobiles to industrial equipment. Basis of Presentation The Company’s accompanying unaudited Consolidated Financial Statements have been prepared in accordance with U.S. Generally Accepted Accounting Principles (“GAAP”) for interim financial information, the instructions to Form 10 -Q and Article 10 of Regulation S-X. Accordingly, certain information and disclosures normally included in the consolidated balance sheet, statements of net income and comprehensive income and cash flows prepared in conformity with U.S. GAAP have been condensed or omitted as permitted by such rules and regulations, although the Company believes that the disclosures made are adequate to make the information not misleading. They have been prepared in accordance with accounting policies described in the Company’s Annual Report on Form 10 -K for the year ended December 31, 2016, which should be read in conjunction with the disclosures therein. In the opinion of management, all adjustments considered necessary for a fair presentation have been included and are of a normal, recurring nature. Operating results for interim periods are not necessarily indicative of annual operating results. Goodwill and Indefinite-Lived Intangible Assets The Company annually tests goodwill and indefinite-lived intangible assets for impairment on the first day of its fiscal fourth quarter or at other dates if there is an event or change in circumstances that indicates the asset may be impaired. Management determines the fair value of each of its reporting units by using a discounted cash flow model (which includes forecasted five -year income statement and working capital projections, a market-based weighted average cost of capital and terminal values after five years) to estimate market value. In addition, the Company compares its derived enterprise value on a consolidated basis to the Company’s market capitalization as of its test date to ensure its derived value approximates the market value of the Company when taken as a whole. Factors the Company considers important when performing the impairment tests, which could result in changes to its estimates, include underperformance relative to historical or projected future operating results and declines in acquisitions and trading multiples. Due to the diverse end user base and non-discretionary product demand, the Company does not believe its future operating results will vary significantly relative to its historical and projected future operating results. However, it is possible that impairment charges could be recognized for the relays reporting unit if there are declines in profitability or projected future operating results due to changes in volume, market pricing, cost, or the business environment. As of the most recent annual test conducted on October 2, 2016, the Company concluded the fair value of the relays reporting unit exceeded its carrying value of invested capital and therefore, no potential goodwill impairment existed. As of the 2016 annual test date, the relays reporting unit had $41.4 million of goodwill and intangible assets and the excess of fair value over the carrying value of invested capital was 15%. As of April 1, 2017, there were no events or circumstances that indicate the Relays intangible assets were impaired. Recently Adopted Accounting Standards In July 2015, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2015 - 11 – “Inventory (Topic 330): Simplifying the Measurement of Inventory,” which simplifies the measurement of inventory by requiring inventory to be measured at the lower of cost and net realizable value. The update is effective for financial statements issued for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years. The Company adopted the new standard on January 1, 2017. The adoption of the update did not have a material impact on the Company’s consolidated financial statements. As a result of the adoption of the update, inventories are stated at the lower of cost or net realizable value. Cost is principally determined using the first -in, first -out method. The Company maintains excess and obsolete allowances against inventory to reduce the carrying value to the expected net realizable value. These allowances are based upon a combination of factors including historical sales volume, market conditions, lower of cost or market analysis and expected realizable value of the inventory. In March 2016, the FASB issued ASU No. 2016 - 09 – “Improvements to Employee Share-Based Payment Accounting,” which amends ASC 718, “Compensation – Stock Compensation.” The update simplifies several aspects of the accounting for employee share-based payment transactions, including accounting for income taxes, forfeitures, and statutory withholding requirements, as well as classification in the Consolidated Statements of Cash Flows. The update is effective for financial statements issued for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years. The Company adopted the new standard on January 1, 2017. As a result of the adoption, on a prospective basis, the Company recognized $0.5 million of excess tax benefits from stock-based compensation as a discrete item in income tax expense for the three months ended April 1, 2017. Historically, these amounts were recorded as additional paid-in capital. The Company also elected to apply the change prospectively to the Consolidated Statement of Cash Flows. As a result, on a prospective basis, share-based payments will be reported as operating activities in the Consolidated Statement of Cash Flows. The Company elected not to change its policy on accounting for forfeitures and will continue to estimate a requisite forfeiture rate. Additional amendments to the accounting for income taxes and minimum statutory withholding requirements had no impact on the results of operations. Recently Issued Accounting Standards In May 2014, the FASB issued ASU No. 2014 - 09, “Revenue from Contracts with Customers” (Topic 606) which supersedes the revenue recognition requirements in ASC 605, “Revenue Recognition.” This ASU provides a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and will supersede most current revenue recognition guidance. The guidance permits two implementation approaches, one requiring retrospective application of the new standard with restatement of prior years and one requiring prospective application of the new standard with disclosure of results under old standards. In August, 2015, the FASB issued ASU No. 2015 - 14, which postponed the effective date of ASU No. 2014 - 09 to fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted on the original effective date of fiscal years beginning after December 15, 2016. The Company is in the process of performing its initial assessment of the potential impact on its consolidated financial statements and has not concluded on its adoption methodology. While the Company is currently assessing the impact of the new standards, the Company’s revenue is primarily generated from the sale of finished products to customers. Those sales predominantly contain a single delivery element and revenue is recognized at a single point in time when ownership, risks, and rewards transfer. These are largely un-affected by the new standard. The Company does not expect this new guidance to have a material impact on the amount of overall sales recognized; however, the timing of sales on certain projects may be affected. The Company has not yet quantified this potential impact. In February 2016, the FASB issued ASU No. 2016 - 02, "Leases" (Topic 842). This ASU requires lessees to recognize, on the balance sheet, assets and liabilities for the rights and obligations created by leases of greater than twelve months. The accounting by lessors will remain largely unchanged. The ASU is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. Adoption will require a modified retrospective transition. The Company is currently evaluating the impact of this ASU on its consolidated financial statements. In January 2017, the FASB issued ASU No. 2017 - 04, “Intangibles-Goodwill and Other” (Topic 350). This ASU modifies the concept of impairment from the condition that exists when the carrying amount of goodwill exceeds its implied fair value to the condition that exists when the carrying amount of a reporting unit exceeds its fair value. An entity no longer will determine goodwill impairment by calculating the implied fair value of goodwill by assigning the fair value of a reporting unit to all of its assets and liabilities as if that reporting unit had been acquired in a business combination. Because the update will eliminate Step 2 from the goodwill impairment test, it should reduce the cost and complexity of evaluating goodwill for impairment. This ASU is effective for annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2020, with early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The Company expects to adopt the new standard in 2017.

Summary of Significant Accounting Policies and Other Information

Nature of Operations

Littelfuse, Inc. and subsidiaries (the “Company”) design, manufacture, and sell circuit protection devices for use in the automotive, electronics, and industrial markets throughout the world. The Company is

one

of the world’s leading suppliers of circuit protection products for the electronics, automotive, and industrial markets, with expanding platforms in sensors and power control components and modules. In addition to circuit protection products and solutions, the Company offers electronic reed switches and sensors, automotive sensors for comfort and safety systems and a comprehensive line of highly reliable electromechanical and electronic switch and control devices for commercial and specialty vehicles, as well as protection relays and power distribution centers for the safe control and distribution of electricity. The Company has a network of global engineering centers and labs that develop new products and product enhancements, provides customer application support and test products for safety, reliability, and regulatory compliance. The Company’s devices protect products in virtually every market that uses electrical energy, from consumer electronics to automobiles to industrial equipment.

Basis of Presentation

The Company’s accompanying unaudited Consolidated Financial Statements have been prepared in accordance with U.S. Generally Accepted Accounting Principles (“GAAP”) for interim financial information, the instructions to Form

-Q and Article

of Regulation S-X. Accordingly, certain information and disclosures normally included in the consolidated balance sheet, statements of net income and comprehensive income and cash flows prepared in conformity with U.S. GAAP have been condensed or omitted as permitted by such rules and regulations, although the Company believes that the disclosures made are adequate to make the information not misleading. They have been prepared in accordance with accounting policies described in the Company’s Annual Report on Form

-K for the year ended

December

31,

2016,

which should be read in conjunction with the disclosures therein.

In the opinion of management, all adjustments considered necessary for a fair presentation have been included and are of a normal, recurring nature. Operating results for interim periods are not necessarily indicative of annual operating results.

Goodwill and Indefinite-Lived Intangible Assets

The Company annually tests goodwill and indefinite-lived intangible assets for impairment on the

first

day of its fiscal

fourth

quarter or at other dates if there is an event or change in circumstances that indicates the asset

may

be impaired. Management determines the fair value of each of its reporting units by using a discounted cash flow model (which includes forecasted

five

-year income statement and working capital projections, a market-based weighted average cost of capital and terminal values after

five

years) to estimate market value. In addition, the Company compares its derived enterprise value on a consolidated basis to the Company’s market capitalization as of its test date to ensure its derived value approximates the market value of the Company when taken as a whole.

Factors the Company considers important when performing the impairment tests, which could result in changes to its estimates, include underperformance relative to historical or projected future operating results and declines in acquisitions and trading multiples. Due to the diverse end user base and non-discretionary product demand, the Company does not believe its future operating results will vary significantly relative to its historical and projected future operating results. However, it is possible that impairment charges could be recognized for the relays reporting unit if there are declines in profitability or projected future operating results due to changes in volume, market pricing, cost, or the business environment. As of the most recent annual test conducted on

October

2016,

the Company concluded the fair value of the relays reporting unit exceeded its carrying value of invested capital and therefore, no potential goodwill impairment existed. As of the

2016

annual test date, the relays reporting unit had

$41.4

million of goodwill and intangible assets and the excess of fair value over the carrying value of invested capital was

15%.

As of

April

2017,

there were no events or circumstances that indicate the Relays intangible assets were impaired.

Recently

Adopted

Accounting Standards

July

2015,

the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No.

2015

– “Inventory (Topic

330):

Simplifying the Measurement of Inventory,” which simplifies the measurement of inventory by requiring inventory to be measured at the lower of cost and net realizable value. The update is effective for financial statements issued for fiscal years beginning after

December

15,

2016,

and interim periods within those fiscal years. The Company adopted the new standard on

January

2017.

The adoption of the update did not have a material impact on the Company’s consolidated financial statements. As a result of the adoption of the update, inventories are stated at the lower of cost or net realizable value. Cost is principally determined using the

first

-in,

first

-out method. The Company maintains excess and obsolete allowances against inventory to reduce the carrying value to the expected net realizable value. These allowances are based upon a combination of factors including historical sales volume, market conditions, lower of cost or market analysis and expected realizable value of the inventory.

March

2016,

the FASB issued ASU No.

2016

– “Improvements to Employee Share-Based Payment Accounting,” which amends ASC

718,

“Compensation – Stock Compensation.” The update simplifies several aspects of the accounting for employee share-based payment transactions, including accounting for income taxes, forfeitures, and statutory withholding requirements, as well as classification in the Consolidated Statements of Cash Flows. The update is effective for financial statements issued for fiscal years beginning after

December

15,

2016,

and interim periods within those fiscal years. The Company adopted the new standard on

January

2017.

As a result of the adoption, on a prospective basis, the Company recognized

$0.5

million of excess tax benefits from stock-based compensation as a discrete item in income tax expense for the

three

months ended

April

2017.

Historically, these amounts were recorded as additional paid-in capital. The Company also elected to apply the change prospectively to the Consolidated Statement of Cash Flows. As a result, on a prospective basis, share-based payments will be reported as operating activities in the Consolidated Statement of Cash Flows. The Company elected not to change its policy on accounting for forfeitures and will continue to estimate a requisite forfeiture rate. Additional amendments to the accounting for income taxes and minimum statutory withholding requirements had no impact on the results of operations.

Recently Issued Accounting Standards

May

2014,

the FASB issued ASU No.

2014

09,

“Revenue from Contracts with Customers” (Topic

606)

which supersedes the revenue recognition requirements in ASC

605,

“Revenue Recognition.” This ASU provides a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and will supersede most current revenue recognition guidance. The guidance permits

two

implementation approaches,

one

requiring retrospective application of the new standard with restatement of prior years and

one

requiring prospective application of the new standard with disclosure of results under old standards. In

August,

2015,

the FASB issued ASU No.

2015

14,

which postponed the effective date of ASU No.

2014

to fiscal years, and interim periods within those fiscal years, beginning after

December

15,

2017,

with early adoption permitted on the original effective date of fiscal years beginning after

December

15,

2016.

The Company is in the process of performing its initial assessment of the potential impact on its consolidated financial statements and has not concluded on its adoption methodology. While the Company is currently assessing the impact of the new standards, the Company’s revenue is primarily generated from the sale of finished products to customers. Those sales predominantly contain a single delivery element and revenue is recognized at a single point in time when ownership, risks, and rewards transfer. These are largely un-affected by the new standard. The Company does not expect this new guidance to have a material impact on the amount of overall sales recognized; however, the timing of sales on certain projects

may

be affected. The Company has not yet quantified this potential impact.

February

2016,

the FASB issued ASU No.

2016

02,

"Leases" (Topic

842).

This ASU requires lessees to recognize, on the balance sheet, assets and liabilities for the rights and obligations created by leases of greater than

twelve

months. The accounting by lessors will remain largely unchanged. The ASU is effective for fiscal years, and interim periods within those fiscal years, beginning after

December

15,

2018,

with early adoption permitted. Adoption will require a modified retrospective transition. The Company is currently evaluating the impact of this ASU on its consolidated financial statements.

January

2017,

the FASB issued ASU No.

2017

04,

“Intangibles-Goodwill and Other” (Topic

350).

This ASU modifies the concept of impairment from the condition that exists when the carrying amount of goodwill exceeds its implied fair value to the condition that exists when the carrying amount of a reporting unit exceeds its fair value. An entity no longer will determine goodwill impairment by calculating the implied fair value of goodwill by assigning the fair value of a reporting unit to all of its assets and liabilities as if that reporting unit had been acquired in a business combination. Because the update will eliminate Step

from the goodwill impairment test, it should reduce the cost and complexity of evaluating goodwill for impairment. This ASU is effective for annual or any interim goodwill impairment tests in fiscal years beginning after

December

15,

2020,

with early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after

January

2017.

The Company expects to adopt the new standard in

2017.