v3.6.0.2

Financial Instruments (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2016
Financial Instruments |
Schedule of available-for-sale securities |
|  | December 31, 2016 |  | December 31, 2015 |
|  | Amortized Cost |  | Gross Unrealized Gain |  | Gross Unrealized (Loss) |  | Estimated Fair Value |  | Amortized Cost |  | Gross Unrealized Gain |  | Gross Unrealized (Loss) |  | Estimated Fair Value |
|  | (in thousands) |
Money market deposits |  | $ | 10,777 |  | $ | — |  | $ | — |  | $ | 10,777 |  | $ | 5,966 |  | $ | — |  | $ | — |  | $ | 5,966 |
U.S. Treasury securities |  |  | 57,846 |  |  | — |  |  | (404) |  |  | 57,442 |  |  | 104,537 |  |  | 1 |  |  | (725) |  |  | 103,813 |
U.S. agency securities |  |  | 56,261 |  |  | — |  |  | (147) |  |  | 56,114 |  |  | 79,491 |  |  | — |  |  | (638) |  |  | 78,853 |
Municipal securities |  |  | 17,478 |  |  | — |  |  | (174) |  |  | 17,304 |  |  | 18,974 |  |  | 2 |  |  | (56) |  |  | 18,920 |
Total |  | $ | 142,362 |  | $ | — |  | $ | (725) |  | $ | 141,637 |  | $ | 208,968 |  | $ | 3 |  | $ | (1,419) |  | $ | 207,552 |
Classified as: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash equivalents |  |  |  |  |  |  |  |  |  |  | $ | 10,777 |  |  |  |  |  |  |  |  |  |  | $ | 5,966 |
Short-term investments |  |  |  |  |  |  |  |  |  |  |  | 130,860 |  |  |  |  |  |  |  |  |  |  |  | 201,586 |
Total |  |  |  |  |  |  |  |  |  |  | $ | 141,637 |  |  |  |  |  |  |  |  |  |  | $ | 207,552 |
Summarized portfolio of available-for-sale securities by contractual maturity |
|  | December 31, 2016 |
|  | Amortized Cost |  | Fair Value |
|  | (in thousands) |
Less than one year |  | $ | 48,265 |  | $ | 48,212 |
Greater than one year but less than five years |  |  | 83,320 |  |  | 82,648 |
Total |  | $ | 131,585 |  | $ | 130,860 |

X
- Definition Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 320 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62557-112803 Reference 2: 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 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27198-111563 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 320 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62586-112803 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27161-111563 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27357-111563 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27290-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of maturities of an entity's investments as well as any other information pertinent to the investments. + References No definition available. + Details
Name: | us-gaap_InvestmentsClassifiedByContractualMaturityDateTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_InvestmentsDebtAndEquitySecuritiesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration