XML 58 R35.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Investments (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract] |
Short-Term and Long-Term Investments Available-for-Sale and Cost Method Investments | Investments classified as short-term consist of the following:
|  | Years Ended December 31, |
|  | 2018 |  |  | 2017 |
Available-for-sale investments: |  |  |  |  |  |  |  |
Time deposits and certificates of deposit |  | $ | 102 |  |  | $ | 9,757 |
Bankers’ acceptance drafts |  |  | 989 |  |  |  | 5,330 |
Asset-backed securities |  |  | 9,113 |  |  |  | 36,990 |
Commercial paper |  |  | 19,359 |  |  |  | 13,750 |
Corporate obligations |  |  | 9,352 |  |  |  | 77,821 |
Municipal bonds |  |  | — |  |  |  | 1,970 |
U.S. treasury obligations |  |  | 13,298 |  |  |  | 28,078 |
U.S. agency obligations |  |  | 21,613 |  |  |  | 35,738 |
|  | $ | 73,826 |  |  | $ | 209,434 |
Investments classified as long-term consist of the following:
|  | Years Ended December 31, |
|  | 2018 |  |  | 2017 |
Available-for-sale investments: |  |  |  |  |  |  |  |
Group insurance contracts |  | $ | 5,890 |  |  | $ | 6,255 |
Cost method investments: |  |  |  |  |  |  |  |
Minority interest in a private company |  |  | 4,400 |  |  |  | 4,400 |
|  | $ | 10,290 |  |  | $ | 10,655 |
Gross Unrealized Gains and (Losses) Aggregated by Investment Category | The following table shows the gross unrealized gains and (losses) aggregated by investment category for available-for-sale investments:
As of December 31, 2018: |  | Cost |  |  | Gross Unrealized Gains |  |  | Gross Unrealized (Losses) |  |  | Estimated Fair Value |
Short-term investments: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Available-for-sale investments: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Time deposits and certificates of deposit |  | $ | 102 |  |  | $ | — |  |  | $ | — |  |  | $ | 102 |
Bankers’ acceptance drafts |  |  | 989 |  |  |  | — |  |  |  | — |  |  |  | 989 |
Asset-backed securities |  |  | 9,121 |  |  |  | 1 |  |  |  | (9 | ) |  |  | 9,113 |
Commercial paper |  |  | 19,504 |  |  |  | — |  |  |  | (145 | ) |  |  | 19,359 |
Corporate obligations |  |  | 9,367 |  |  |  | — |  |  |  | (15 | ) |  |  | 9,352 |
U.S. treasury obligations |  |  | 13,294 |  |  |  | 4 |  |  |  | — |  |  |  | 13,298 |
U.S. agency obligations |  |  | 21,617 |  |  |  | 2 |  |  |  | (6 | ) |  |  | 21,613 |
|  | $ | 73,994 |  |  | $ | 7 |  |  | $ | (175 | ) |  | $ | 73,826 |
As of December 31, 2018: |  | Cost |  |  | Gross Unrealized Gains |  |  | Gross Unrealized (Losses) |  |  | Estimated Fair Value |
Long-term investments: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Available-for-sale investments: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Group insurance contracts |  | $ | 5,546 |  |  | $ | 344 |  |  | $ | — |  |  | $ | 5,890 |
As of December 31, 2017: |  | Cost |  |  | Gross Unrealized Gains |  |  | Gross Unrealized (Losses) |  |  | Estimated Fair Value |
Short-term investments: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Available-for-sale investments: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Time deposits and certificates of deposit |  | $ | 9,756 |  |  | $ | 1 |  |  | $ | — |  |  | $ | 9,757 |
Bankers’ acceptance drafts |  |  | 5,330 |  |  |  | — |  |  |  | — |  |  |  | 5,330 |
Asset-backed securities |  |  | 37,017 |  |  |  | 15 |  |  |  | (42 | ) |  |  | 36,990 |
Commercial paper |  |  | 13,810 |  |  |  | — |  |  |  | (60 | ) |  |  | 13,750 |
Corporate obligations |  |  | 77,788 |  |  |  | 58 |  |  |  | (25 | ) |  |  | 77,821 |
Municipal bonds |  |  | 1,970 |  |  |  | — |  |  |  | — |  |  |  | 1,970 |
U.S. treasury obligations |  |  | 28,054 |  |  |  | 24 |  |  |  | — |  |  |  | 28,078 |
U.S. agency obligations |  |  | 35,728 |  |  |  | 10 |  |  |  | — |  |  |  | 35,738 |
|  | $ | 209,453 |  |  | $ | 108 |  |  | $ | (127 | ) |  | $ | 209,434 |
As of December 31, 2017: |  | Cost |  |  | Gross Unrealized Gains |  |  | Gross Unrealized (Losses) |  |  | Estimated Fair Value |
Long-term investments: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Available-for-sale investments: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Group insurance contracts |  | $ | 6,006 |  |  | $ | 249 |  |  | $ | — |  |  | $ | 6,255 |

X
- Definition Investments classified as short-term and long-term available-for-sale investments and long-term cost method investments. + References No definition available. + Details
Name: | mksi_InvestmentsClassifiedAsShortTermAndLongTermAvailableForSaleInvestmentsAndLongTermCostMethodInvestmentsTableTextBlock
Namespace Prefix: | mksi_
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

X
- Definition Tabular disclosure of the reconciliation of available-for-sale securities from cost basis to fair value. + References No definition available. + Details
Name: | us-gaap_ScheduleOfAvailableForSaleSecuritiesReconciliationTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration