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Marketable Securities (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2016 | Dec. 31, 2015
Cash equivalents and marketable securities |  |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | $ 72,772 | $ 159,673
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | $ (21) | $ (188)
Maximum maturity period of available-for-sale securities (in years) | 3 years | 3 years
Maximum remaining maturity period of available-for-sale securities (in years) | 1 year | 1 year
Fair Value | $ 121,151 | $ 252,737
Amortized Cost | 121,171 | 252,925
Cash Cash Equivalents And Short Term Investments Unrealized Gains | 1 | 0
CashCashEquivalentsAndShortTermInvestmentsUnrealizedLosses | (21) | (188)
Gross Unrealized Gains | 1 | 0
Gross Unrealized Losses | 21 | 188
Cash, fair value | 51,031 | 34,969
Cash | 51,031 | 34,969
Cash, cash equivalents and marketable securities |  |
Fair Value | 172,182 | 287,706
Amortized Cost | 172,202 | 287,894
Money market funds |  |
Cash equivalents and marketable securities |  |
Fair Value | 10,681 | 77,804
Amortized Cost | 10,681 | 77,804
Cash Cash Equivalents And Short Term Investments Unrealized Gains | 0 | 0
CashCashEquivalentsAndShortTermInvestmentsUnrealizedLosses | $ 0 | $ 0
Weighted Rate of Return (as a percent) | 0.41% | 0.12%
US Treasury and Government [Member] |  |
Cash equivalents and marketable securities |  |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | $ 18,395 | $ 14,110
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 0 | (32)
Fair Value | 48,292 | 14,110
Amortized Cost | 48,291 | 14,142
Cash Cash Equivalents And Short Term Investments Unrealized Gains | 1 | 0
CashCashEquivalentsAndShortTermInvestmentsUnrealizedLosses | $ 0 | $ (32)
Weighted Rate of Return (as a percent) | 0.39% | 0.48%
Corporate notes, bonds and commercial paper |  |
Cash equivalents and marketable securities |  |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | $ 54,377 | $ 145,563
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (21) | (156)
Fair Value | 62,178 | 160,823
Amortized Cost | 62,199 | 160,979
Cash Cash Equivalents And Short Term Investments Unrealized Gains | 0 | 0
CashCashEquivalentsAndShortTermInvestmentsUnrealizedLosses | $ (21) | $ (156)
Weighted Rate of Return (as a percent) | 0.66% | 0.45%
Short term marketable securities |  |
Cash equivalents and marketable securities |  |
Fair Value | $ 36,888 | $ 143,942
Cash Equivalents [Member] |  |
Cash equivalents and marketable securities |  |
Fair Value | $ 84,263 | $ 108,795

X
- Definition This item represents the weighted rate of return on marketable securities like money market funds, U.S. government bonds and notes, corporate notes, bonds and commercial paper, corporate securities and cash and cash equivalents. + References No definition available. + Details
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- Definition This item represents the amortized cost of cash, cash equivalents and marketable securities, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any. + References No definition available. + Details
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- Definition This element represents the aggregate of cash, cash equivalents and marketable securities reported on the balance sheet at period end measured at fair value by the entity. + References No definition available. + Details
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- Definition This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the company may deposit additional funds at any time and also effectively may withdraw funds at any time without prior notice or penalty. + References No definition available. + Details
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- Definition Represents the maximum maturity period of securities invested by the entity. + References No definition available. + Details
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- Definition This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.2) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27337-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27290-111563 + Details
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- Definition Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Excludes cash and cash equivalents within disposal group and discontinued operation. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Cash -URI http://asc.fasb.org/extlink&oid=6506951 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.1) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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