Fair Value of Financial Instruments | Fair Value of Financial Instruments Available-for-sale investments within cash equivalents and investments consist of the following: October 31, 2015 Amortized Cost Unrealized Gains Unrealized Losses Estimated Fair Value (in thousands) U.S. agency securities $ 104,668 $ 16 $ (8 ) $ 104,676 Commercial paper 120,295 11 (1 ) 120,305 Corporate bonds 265,127 91 (281 ) 264,937 U.S. government bonds 43,081 3 (28 ) 43,056 Foreign government bonds 8,630 5 — 8,635 Money market funds 100,704 — — 100,704 Total $ 642,505 $ 126 $ (318 ) $ 642,313 July 31, 2015 Amortized Cost Unrealized Gains Unrealized Losses Estimated Fair Value (in thousands) U.S. agency securities $ 82,946 $ 21 $ (4 ) $ 82,963 Commercial paper 142,822 13 (4 ) 142,831 Corporate bonds 281,942 47 (216 ) 281,773 U.S. government bonds 32,529 13 (2 ) 32,540 Foreign government bonds 8,663 7 (2 ) 8,668 Certificate of deposit 2,700 — — 2,700 Money market funds 88,319 — — 88,319 Total $ 639,921 $ 101 $ (228 ) $ 639,794 The following table shows the gross unrealized losses and fair value of the Company’s investments with unrealized losses, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position: October 31, 2015 Less Than 12 Months 12 Months or Greater Total Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses (in thousands) Commercial paper $ 56,926 $ (1 ) $ — $ — $ 56,926 $ (1 ) U.S. agency securities 35,508 (8 ) — — 35,508 (8 ) Corporate bonds 142,383 (280 ) 5,875 (1 ) 148,258 (281 ) U.S. government bonds 25,057 (28 ) — — 25,057 (28 ) Foreign government bonds 2,900 * — — 2,900 * Total $ 262,774 $ (317 ) $ 5,875 $ (1 ) $ 268,649 $ (318 ) * Amount less than one thousand dollars. As of October 31, 2015 , the Company had 96 investments in a gross unrealized loss position. The unrealized losses on its available-for-sale securities were primarily a result of changes in interest rates subsequent to the initial purchase of these securities. The Company does not intend to sell, nor believe it will need to sell, these securities before recovering the associated unrealized losses. The Company does not consider any portion of the unrealized losses at October 31, 2015 to be an other-than-temporary impairment, nor are any unrealized losses considered to be credit losses. The Company has recorded the securities at fair value in its condensed consolidated balance sheets, with unrealized gains and losses reported as a component of accumulated other comprehensive loss. The amounts of realized gains and losses reclassified into earnings are based on the specific identification of the securities sold. The realized gains and losses from sales of securities in the periods presented were not significant. The following table summarizes the contractual maturities of the Company’s available-for-sale securities as of October 31, 2015 : Less Than 12 Months 12 to 36 Months Total (in thousands) U.S. agency securities $ 78,848 $ 25,828 $ 104,676 Commercial paper 120,305 — 120,305 Corporate bonds 178,710 86,227 264,937 U.S. government bonds 27,993 15,063 43,056 Foreign government bonds 8,635 — 8,635 Money market funds 100,704 — 100,704 Total $ 515,195 $ 127,118 $ 642,313 Fair value is defined as the exchange price that would be received for an asset or an exit price paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The current accounting guidance for fair value measurements defines a three-level valuation hierarchy for disclosures as follows: Level 1—Unadjusted quoted prices in active markets for identical assets or liabilities; Level 2—Inputs other than quoted prices included within Level 1 that are observable, unadjusted quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data; and Level 3—Unobservable inputs that are supported by little or no market activity, which require the Company to develop its own assumptions. The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The carrying value of the Company’s accounts receivable, accounts payable and accrued liabilities approximates their fair value due to the short-term nature of these instruments. The Company bases the fair value of its Level 1 financial instruments, which are in active markets, using quoted market prices for identical instruments. The Company obtains the fair value of its Level 2 financial instruments, which are not in active markets, from a third-party professional pricing service using quoted market prices for identical or comparable instruments, rather than direct observations of quoted prices in active markets. The Company’s professional pricing service gathers observable inputs for all of its fixed income securities from a variety of industry data providers (e.g. large custodial institutions) and other third-party sources. Once the observable inputs are gathered, all data points are considered and an average price is determined. The Company validates the quoted market prices provided by its primary pricing service by comparing their assessment of the fair values of its Level 2 investment portfolio balance against the fair values of its Level 2 investment portfolio balance provided by its investment managers. The Company’s investment managers use similar techniques to its professional pricing service to derive pricing as described above. The Company did not have any Level 3 financial assets or liabilities as of October 31, 2015 or July 31, 2015 . The following tables summarize the Company’s financial assets measured at fair value on a recurring basis, by level within the fair value hierarchy as of October 31, 2015 and July 31, 2015 : October 31, 2015 Level 1 Level 2 Level 3 Total (in thousands) Assets Cash and cash equivalents: Commercial paper $ — $ 70,691 $ — $ 70,691 Money market funds 100,704 — — 100,704 Short-term investments: U.S. agency securities — 78,848 — 78,848 Commercial paper — 49,614 — 49,614 Corporate bonds — 178,710 — 178,710 U.S. government bonds — 27,993 — 27,993 Foreign government bonds — 8,635 — 8,635 Long-term investments: U.S. agency securities — 25,828 — 25,828 U.S. government bonds — 15,063 — 15,063 Corporate bonds — 86,227 — 86,227 Total assets $ 100,704 $ 541,609 $ — $ 642,313 July 31, 2015 Level 1 Level 2 Level 3 Total (in thousands) Assets Cash and cash equivalents: Commercial paper $ — $ 86,085 $ — $ 86,085 Money market funds 88,319 — — 88,319 Short-term investments: U.S. agency securities — 68,212 — 68,212 Commercial paper — 56,746 — 56,746 U. S. government bonds — 19,983 — 19,983 Foreign government bonds — 8,668 — 8,668 Corporate bonds — 202,964 — 202,964 Certificate of deposit — 2,700 — 2,700 Long-term investments: U.S. agency securities — 14,751 — 14,751 Corporate bonds — 78,809 — 78,809 U.S. government bonds — 12,557 — 12,557 Total assets $ 88,319 $ 551,475 $ — $ 639,794 |