Significant Accounting Policies (Policy)	3 Months Ended
Significant Accounting Policies (Policy)	Mar. 31, 2019
Accounting Policies [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements Leases In February 2016, the Financial Accounting Standards Board issued an accounting standard update on the accounting for leases (“ASC 842”). The new guidance requires that lessees in a leasing arrangement recognize a right-of-use (“ROU”) asset and a lease liability for most leases (other than leases that meet the definition of a short-term lease). The Company adopted this standard as of January 1, 2019 using a modified retrospective approach, and recognized a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. In addition, the Company elected the package of practical expedients permitted under the transition guidance within the new standard, which among other things, allowed the Company to carry forward the historical lease classification and not reassess whether any expired or existing contract is a lease or contains a lease. Adoption of this standard had a material impact in the Company’s condensed consolidated balance sheets, but did not have an impact on its condensed consolidated income statements. The most significant impact was the recognition of ROU assets and lease liabilities for operating leases, while its accounting for finance leases remained substantially unchanged. Adoption of the new standard resulted in the recording of additional right-of-use assets for operating leases (net of previously recorded lease losses related to the consolidation of leased facilities of $42.2 million and deferred rent liability of $20.5 million under the old guidance) of approximately $194.5 million and operating lease liabilities of approximately $256.4 million, as of January 1, 2019. The difference between the additional lease assets and lease liabilities, net of the deferred tax impact, was recorded as an adjustment to retained earnings of $0.8 million. Adoption of this standard had no impact to cash from or used in operating, financing, or investing in the Company’s condensed consolidated cash flows statements. Adoption of this standard had no impact on the Company's debt covenant compliance under its current agreement or on liquidity. See Note 19 for additional information regarding the Company’s leases. Premium Amortization on Call Debt Securities In March 2017, the Financial Accounting Standards Board issued an accounting standard update on the accounting for amortization of premium costs on purchased callable debt securities. The new guidance amends the amortization period for certain purchased callable debt securities held at a premium, shortening such period to the earliest call date. The standard does not require any accounting change for debt securities held at a discount; the discount continues to be amortized to maturity. The Company adopted the standard effective January 1, 2019 on a modified retrospective basis. The adoption of this standard did not have a material impact on the Company's condensed consolidated financial position, results of operations and cash flows. Accounting for Cloud Computing Costs In August 2018, the Financial Accounting Standards Board issued an accounting standard update on the accounting for implementation costs incurred by customers in cloud computing arrangements that are service contracts. The new guidance aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. The Company early adopted this standard on a prospective basis effective January 1, 2019. Adoption of this standard did not have a material impact on the Company's condensed consolidated financial position, results of operations and cash flows. Fair Value Measurements In August 2018, the Financial Accounting Standards Board issued an accounting standard update on fair value measurements. The new guidance modifies the disclosure requirements on fair value measurements by removing certain disclosure requirements related to the fair value hierarchy, modifying existing disclosure requirements related to measurement uncertainty, and adding new disclosure requirements. The new guidance is effective for annual reporting periods beginning after December 15, 2019, and interim periods within those fiscal years, and early adoption is permitted. The adoption of this standard is not expected to have a material impact on the Company's condensed consolidated financial position, results of operations and cash flows.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. Significant estimates made by management include the standalone selling price related to revenue recognition, the provision for doubtful accounts receivable, the provision to reduce obsolete or excess inventory to market, the provision for estimated returns, as well as sales allowances, the assumptions used in the valuation of stock-based awards, the assumptions used in the discounted cash flows to mark certain of its investments to market, the valuation of the Company’s goodwill, net realizable value of product related and other intangible assets, the provision for income taxes, valuation allowance for deferred tax assets, uncertain tax positions, and the amortization and depreciation periods for contract acquisition costs, intangible and long-lived assets. While the Company believes that such estimates are fair when considered in conjunction with the condensed consolidated financial position and results of operations taken as a whole, the actual amounts of such items, when known, will vary from these estimates.
Available-for-sale Investments	Available-for-sale Investments Short-term and long-term available-for-sale investments as of March 31, 2019 and December 31, 2018 primarily consist of agency securities, corporate securities, municipal securities and government securities. Investments classified as available-for-sale are stated at fair value with unrealized gains and losses, net of taxes, reported in Accumulated other comprehensive loss. The Company classifies its available-for-sale investments as current and non-current based on their actual remaining time to maturity. The Company does not recognize changes in the fair value of its available-for-sale investments in income unless a decline in value is considered other-than-temporary in accordance with the authoritative guidance. The Company’s investment policy is designed to limit exposure to any one issuer depending on credit quality. The Company uses information provided by third parties to adjust the carrying value of certain of its investments to fair value at the end of each period. Fair values are based on a variety of inputs and may include interest rates, known historical trades, yield curve information, benchmark data, prepayment speeds, credit quality and broker/dealer quotes. See Note 6 for additional information regarding the Company’s investments.
Foreign Currency	Foreign Currency The functional currency for all of the Company’s wholly-owned foreign subsidiaries is the U.S. dollar. Monetary assets and liabilities of such subsidiaries are remeasured into U.S. dollars at exchange rates in effect at the balance sheet date, and revenues and expenses are remeasured at average rates prevailing during the year. Foreign currency transaction gains and losses are the result of exchange rate changes on transactions denominated in currencies other than the functional currency, including U.S. dollars. The remeasurement of those foreign currency transactions is included in determining net income or loss for the period of exchange.
Accounting for Stock-Based Compensation Plans	Accounting for Stock-Based Compensation Plans The Company has various stock-based compensation plans for its employees and outside directors and accounts for stock-based compensation arrangements in accordance with the authoritative guidance, which requires the Company to measure and record compensation expense in its condensed consolidated financial statements using a fair value method. See Note 8 for further information regarding the Company’s stock-based compensation plans.

Disclosure of accounting policy for investments in financial assets, including marketable securities (debt and equity securities with readily determinable fair values), investments accounted for under the equity method and cost method, securities borrowed and loaned, and repurchase and resale agreements. For marketable securities, the disclosure may include the entity's accounting treatment for transfers between investment categories and how the fair values for such securities are determined. Also, for all investments, an entity may describe its policy for assessing, recognizing and measuring impairment of the investment.