Summary of Significant Accounting Policies	3 Months Ended
Mar. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited consolidated financial statements of Quidel Corporation and its subsidiaries (the “Company”) have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments considered necessary for a fair presentation (consisting of normal recurring accruals) have been included. The information at March 31, 2018, and for the three months ended March 31, 2018 and 2017, is unaudited. For further information, refer to the Company’s consolidated financial statements and notes thereto for the year ended December 31, 2017 included in the Company’s 2017 Annual Report on Form 10-K. Operating results for any quarter are historically seasonal in nature and are not necessarily indicative of the results expected for the full year. For 2018 and 2017, the Company’s fiscal year will end or has ended on December 30, 2018 and December 31, 2017, respectively. For 2018 and 2017, the Company’s first quarter ended on April 1, 2018 and April 2, 2017, respectively. For ease of reference, the calendar quarter end dates are used herein. The three month periods ended March 31, 2018 and 2017 each included 13 weeks. Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the U.S. requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Significant Accounting Policies During the three months ended March 31, 2018, there have been no changes to our significant accounting policies as described in our Annual Report on Form 10-K for the fiscal year ended December 31, 2017, except as described below. Revenue Recognition The Company records revenues primarily from product sales. These revenues are recorded net of rebates and other discounts. These rebates and discounts are estimated at the time of sale, and are largely driven by various customer program offerings, including special pricing agreements, promotions and other volume-based incentives. Revenue is recognized when control of the products is transferred to the customers in an amount that reflects the consideration the Company expects to receive from the customers in exchange for those products and services. This process involves identifying the contract with a customer, determining the performance obligations in the contract, determining the contract price, allocating the contract price to the distinct performance obligations in the contract and recognizing revenue when the performance obligations have been satisfied. A performance obligation is considered distinct from other obligations in a contract when it provides a benefit to the customer either on its own or together with other resources that are readily available to the customer and is separately identified in the contract. Performance obligation is considered to be satisfied once the control of a product is transferred to the customer, meaning the customer has the ability to use and obtain the benefit of the good or service. The Company recognizes revenue for satisfied performance obligations only when there are no uncertainties regarding payment terms or transfer of control. A portion of product sales includes revenues for diagnostic kits, which are utilized on leased instrument systems under the Company’s “reagent rental” program. The reagent rental program provides customers the right to use the instruments at no separate cost to the customer in consideration for a multi-year agreement to purchase annual minimum amounts of consumables (“reagents” or “diagnostic kits”). When an instrument is placed with a customer under a reagent rental agreement, the Company retains title to the equipment and it remains capitalized on the Company’s Consolidated Balance Sheets as property, plant and equipment. The instrument is depreciated on a straight-line basis over the lower of the lease term or life of the instrument. Depreciation expense is recorded in cost of sales included in the Consolidated Statements of Income. Instrument and consumables under the reagent rental agreements are deemed two distinct performance obligations. Though the instrument and consumables do not have any use to customers without one another, they are not highly interdependent because they do not significantly affect each other. The Company would be able to fulfill its promise to transfer the instrument even if its customers did not purchase any consumables and the Company would be able to fulfill its promise to provide the consumables even if customers acquired instruments separately. Contract price will be allocated between these two performance obligations based on their relative standalone selling prices. The instrument is considered an operating lease and revenue allocated to the instrument will be separately disclosed if material. Reclassifications The Company recorded a reclassification of $1.6 million for the three months ended March 31, 2017 from amortization of intangible assets from acquired business and technology to cost of sales expense as previously reported in the Consolidated Statements of Income. In addition, the Company recorded a reclassification of $0.7 million for the three months ended March 31, 2017 from amortization of intangible assets from acquired business and technology to sales and marketing expense to conform to current year presentation. These reclassifications did not impact the net income as previously reported or any prior amounts reported on the Consolidated Balance Sheets, Statements of Cash Flows or Statements of Comprehensive Income. The Company also recorded immaterial reclassifications of acquisition and integration costs totaling $0.1 million for the three months ended March 31, 2017 from general and administrative expense to acquisition and integration costs as previously reported in the Consolidated Statements of Income to conform to current year presentation. The Company believes these reclassifications provide greater clarity and insight into the consolidated financial statements for the periods presented. The reclassification did not impact the net income as previously reported or any prior amounts reported on the Consolidated Balance Sheets, Statements of Cash Flows or Statements of Comprehensive Income. Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued guidance codified in Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers, which amends the guidance in former ASC 605, Revenue Recognition (“ASU 2014-09”). The standard’s core principle is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. In doing so, companies will need to use more judgment and make more estimates than under current authoritative guidance. These may include identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price and allocating the transaction price to each separate performance obligation. The FASB has issued several amendments to the new standard, which include clarification of accounting guidance related to identification of performance obligations, intellectual property licenses and principal vs. agent considerations. ASU 2014-09 and all subsequent amendments (collectively, the “ASC 606”) are effective for public entities for annual reporting periods beginning after December 15, 2017, including interim periods therein. The Company adopted ASC 606 on January 1, 2018, using the modified retrospective transition method applied to those contracts which were not completed as of that date. The cumulative effect of applying the new revenue standard to all incomplete contracts as of January 1, 2018 was not material and, therefore, did not result in an adjustment to retained earnings. The adoption of ASC 606 did not have a material impact on the Company's consolidated financial position, results of operations, equity or cash flows as of the adoption date or for the three months ended March 31, 2018. In February 2016, the FASB issued guidance codified in ASU 2016-02 (Topic 842), Leases. The guidance requires a lessee to recognize a lease liability for the obligation to make lease payments and a right-to-use asset representing the right to use the underlying asset for the lease term on the balance sheet. The guidance is effective for fiscal years beginning after December 15, 2018 including interim periods within those years. Currently, the standard will be adopted on a modified retrospective transition basis for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The FASB has proposed an alternative method to adopt the lease standard by recognizing a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. While the Company is continuing to assess the effects of adoption, the Company believes the new standard will have a material effect on the consolidated financial statements and disclosures. We expect substantially all real-estate operating lease commitments to be recognized as lease liabilities with corresponding right-of-use assets upon adoption, resulting in a significant increase in the assets and liabilities on the consolidated balance sheet. The Company is currently evaluating the impact of Topic 842 on the consolidated financial statements as it relates to other aspects of its business. In January 2017, the FASB issued guidance codified in ASU 2017-04, Intangibles-Goodwill and Other (Topic 350) Simplifying the Test for Goodwill Impairment (“ASU 2017-04”). Under this new guidance, an entity will no longer 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. Instead, an entity will compare the fair value of a reporting unit with its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit's fair value. The guidance is effective for fiscal years beginning after December 15, 2019 including interim periods therein. The Company is currently evaluating the impact of this guidance and expects to adopt the standard in the first quarter of 2020.

Summary of Significant Accounting Policies

Basis of Presentation

The accompanying unaudited consolidated financial statements of Quidel Corporation and its subsidiaries (the “Company”) have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments considered necessary for a fair presentation (consisting of normal recurring accruals) have been included.

The information at March 31, 2018, and for the three months ended March 31, 2018 and 2017, is unaudited. For further information, refer to the Company’s consolidated financial statements and notes thereto for the year ended December 31, 2017 included in the Company’s 2017 Annual Report on Form 10-K. Operating results for any quarter are historically seasonal in nature and are not necessarily indicative of the results expected for the full year.

For 2018 and 2017, the Company’s fiscal year will end or has ended on December 30, 2018 and December 31, 2017, respectively. For 2018 and 2017, the Company’s first quarter ended on April 1, 2018 and April 2, 2017, respectively. For ease of reference, the calendar quarter end dates are used herein. The three month periods ended March 31, 2018 and 2017 each included 13 weeks.

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the U.S. requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Significant Accounting Policies

During the three months ended March 31, 2018, there have been no changes to our significant accounting policies as described in our Annual Report on Form 10-K for the fiscal year ended December 31, 2017, except as described below.

Revenue Recognition

The Company records revenues primarily from product sales. These revenues are recorded net of rebates and other discounts. These rebates and discounts are estimated at the time of sale, and are largely driven by various customer program offerings, including special pricing agreements, promotions and other volume-based incentives. Revenue is recognized when control of the products is transferred to the customers in an amount that reflects the consideration the Company expects to receive from the customers in exchange for those products and services. This process involves identifying the contract with a customer, determining the performance obligations in the contract, determining the contract price, allocating the contract price to the distinct performance obligations in the contract and recognizing revenue when the performance obligations have been satisfied. A performance obligation is considered distinct from other obligations in a contract when it provides a benefit to the customer either on its own or together with other resources that are readily available to the customer and is separately identified in the contract. Performance obligation is considered to be satisfied once the control of a product is transferred to the customer, meaning the customer has the ability to use and obtain the benefit of the good or service. The Company recognizes revenue for satisfied performance obligations only when there are no uncertainties regarding payment terms or transfer of control.

A portion of product sales includes revenues for diagnostic kits, which are utilized on leased instrument systems under the Company’s “reagent rental” program. The reagent rental program provides customers the right to use the instruments at no separate cost to the customer in consideration for a multi-year agreement to purchase annual minimum amounts of consumables (“reagents” or “diagnostic kits”). When an instrument is placed with a customer under a reagent rental agreement, the Company retains title to the equipment and it remains capitalized on the Company’s Consolidated Balance Sheets as property, plant and equipment. The instrument is depreciated on a straight-line basis over the lower of the lease term or life of the instrument. Depreciation expense is recorded in cost of sales included in the Consolidated Statements of Income. Instrument and consumables under the reagent rental agreements are deemed two distinct performance obligations. Though the instrument and consumables do not have any use to customers without one another, they are not highly interdependent because they do not significantly affect each other. The Company would be able to fulfill its promise to transfer the instrument even if its customers did not purchase any consumables and the Company would be able to fulfill its promise to provide the consumables even if customers acquired instruments separately. Contract price will be allocated between these two performance obligations based on their relative standalone selling prices. The instrument is considered an operating lease and revenue allocated to the instrument will be separately disclosed if material.

Reclassifications

The Company recorded a reclassification of $1.6 million for the three months ended March 31, 2017 from amortization of intangible assets from acquired business and technology to cost of sales expense as previously reported in the Consolidated Statements of Income. In addition, the Company recorded a reclassification of $0.7 million for the three months ended March 31, 2017 from amortization of intangible assets from acquired business and technology to sales and marketing expense to conform to current year presentation. These reclassifications did not impact the net income as previously reported or any prior amounts reported on the Consolidated Balance Sheets, Statements of Cash Flows or Statements of Comprehensive Income.

The Company also recorded immaterial reclassifications of acquisition and integration costs totaling $0.1 million for the three months ended March 31, 2017 from general and administrative expense to acquisition and integration costs as previously reported in the Consolidated Statements of Income to conform to current year presentation. The Company believes these reclassifications provide greater clarity and insight into the consolidated financial statements for the periods presented. The reclassification did not impact the net income as previously reported or any prior amounts reported on the Consolidated Balance Sheets, Statements of Cash Flows or Statements of Comprehensive Income.

Recent Accounting Pronouncements

In May 2014, the Financial Accounting Standards Board (“FASB”) issued guidance codified in Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers, which amends the guidance in former ASC 605, Revenue Recognition (“ASU 2014-09”). The standard’s core principle is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. In doing so, companies will need to use more judgment and make more estimates than under current authoritative guidance. These may include identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price and allocating the transaction price to each separate performance obligation. The FASB has issued several amendments to the new standard, which include clarification of accounting guidance related to identification of performance obligations, intellectual property licenses and principal vs. agent considerations. ASU 2014-09 and all subsequent amendments (collectively, the “ASC 606”) are effective for public entities for annual reporting periods beginning after December 15, 2017, including interim periods therein.

The Company adopted ASC 606 on January 1, 2018, using the modified retrospective transition method applied to those contracts which were not completed as of that date. The cumulative effect of applying the new revenue standard to all incomplete contracts as of January 1, 2018 was not material and, therefore, did not result in an adjustment to retained earnings. The adoption of ASC 606 did not have a material impact on the Company's consolidated financial position, results of operations, equity or cash flows as of the adoption date or for the three months ended March 31, 2018.

In February 2016, the FASB issued guidance codified in ASU 2016-02 (Topic 842), Leases. The guidance requires a lessee to recognize a lease liability for the obligation to make lease payments and a right-to-use asset representing the right to use the underlying asset for the lease term on the balance sheet. The guidance is effective for fiscal years beginning after December 15, 2018 including interim periods within those years. Currently, the standard will be adopted on a modified retrospective transition basis for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The FASB has proposed an alternative method to adopt the lease standard by recognizing a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. While the Company is continuing to assess the effects of adoption, the Company believes the new standard will have a material effect on the consolidated financial statements and disclosures. We expect substantially all real-estate operating lease commitments to be recognized as lease liabilities with corresponding right-of-use assets upon adoption, resulting in a significant increase in the assets and liabilities on the consolidated balance sheet. The Company is currently evaluating the impact of Topic 842 on the consolidated financial statements as it relates to other aspects of its business.

In January 2017, the FASB issued guidance codified in ASU 2017-04, Intangibles-Goodwill and Other (Topic 350) Simplifying the Test for Goodwill Impairment (“ASU 2017-04”). Under this new guidance, an entity will no longer 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. Instead, an entity will compare the fair value of a reporting unit with its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit's fair value. The guidance is effective for fiscal years beginning after December 15, 2019 including interim periods therein. The Company is currently evaluating the impact of this guidance and expects to adopt the standard in the first quarter of 2020.