XML 79 R66.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Stockholders' Equity - Convertible Preferred Stock and Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Millions |  | 12 Months Ended |
--- | --- | --- | ---
Mar. 26, 2018 | Dec. 31, 2018 | Dec. 31, 2017 | Mar. 27, 2018
Class of Stock [Line Items] |  |  |  |
Preferred stock, shares authorized (in shares) |  | 240,000,000 | 0 |
Preferred stock, shares outstanding (in shares) |  | 0 | 0 |
Preferred stock, per share price at issuance (in dollars per share) |  |  |  | $ 21.00
Class A common stock |  |  |  |
Class of Stock [Line Items] |  |  |  |
Shares issued in conversion (in shares) |  | 0 |  |
Class B common stock |  |  |  |
Class of Stock [Line Items] |  |  |  |
Shares converted in conversion (in shares) |  | 157,000,000 |  |
Convertible preferred stock |  |  |  |
Class of Stock [Line Items] |  |  |  |
Preferred stock, shares authorized (in shares) |  | 0 | 151,200,000.0 |
Preferred stock, shares outstanding (in shares) |  | 0 | 147,600,000 |
Aggregate liquidation preference |  |  | $ 624.7 |
Series A Convertible Preferred Stock |  |  |  |
Class of Stock [Line Items] |  |  |  |
Preferred stock, shares authorized (in shares) |  |  | 63,900,000 |
Preferred stock, shares outstanding (in shares) |  |  | 63,900,000 |
Preferred stock, per share price at issuance (in dollars per share) |  |  | $ 0.09 |
Aggregate liquidation preference |  |  | $ 6.0 |
Preferred stock, dividend per share amount (in dollars per share) |  |  | $ 0.02 |
Series A-1 Convertible Preferred Stock |  |  |  |
Class of Stock [Line Items] |  |  |  |
Preferred stock, shares authorized (in shares) |  |  | 52,000,000 |
Preferred stock, shares outstanding (in shares) |  |  | 51,900,000 |
Preferred stock, per share price at issuance (in dollars per share) |  |  | $ 0.03 |
Aggregate liquidation preference |  |  | $ 1.3 |
Preferred stock, dividend per share amount (in dollars per share) |  |  | $ 0.02 |
Series B Convertible Preferred Stock |  |  |  |
Class of Stock [Line Items] |  |  |  |
Preferred stock, shares authorized (in shares) |  |  | 19,500,000 |
Preferred stock, shares outstanding (in shares) |  |  | 19,500,000 |
Preferred stock, per share price at issuance (in dollars per share) |  |  | $ 13.58 |
Aggregate liquidation preference |  |  | $ 264.8 |
Preferred stock, dividend per share amount (in dollars per share) |  |  | $ 1.08 |
Series C Convertible Preferred Stock |  |  |  |
Class of Stock [Line Items] |  |  |  |
Preferred stock, shares authorized (in shares) |  |  | 15,800,000 |
Preferred stock, shares outstanding (in shares) |  |  | 12,300,000 |
Preferred stock, per share price at issuance (in dollars per share) |  |  | $ 28.65 |
Aggregate liquidation preference |  |  | $ 352.6 |
Preferred stock, dividend per share amount (in dollars per share) |  |  | $ 2.30 |
Conversion of Convertible Preferred Stock to Class B Common Stock | Class B common stock |  |  |  |
Class of Stock [Line Items] |  |  |  |
Shares issued in conversion (in shares) | 147,310,563 |  |  |
Conversion of Convertible Preferred Stock to Class B Common Stock | Convertible preferred stock |  |  |  |
Class of Stock [Line Items] |  |  |  |
Shares converted in conversion (in shares) | 147,310,563 |  |  |
Conversion of Convertible Preferred Stock to Class A Common Stock | Class A common stock |  |  |  |
Class of Stock [Line Items] |  |  |  |
Shares issued in conversion (in shares) | 258,620 |  |  |
Conversion of Convertible Preferred Stock to Class A Common Stock | Convertible preferred stock |  |  |  |
Class of Stock [Line Items] |  |  |  |
Shares converted in conversion (in shares) | 258,620 |  |  |

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_ClassOfStockLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of shares converted in a noncash (or part noncash) transaction. Noncash is defined as transactions during a period that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4313-108586 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4332-108586 + Details
Name: | us-gaap_ConversionOfStockSharesConverted1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of new shares issued in the conversion of stock in a noncash (or part noncash) transaction. Noncash is defined as transactions during a period that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4332-108586 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4313-108586 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586 + Details
Name: | us-gaap_ConversionOfStockSharesIssued1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount per share used to calculated dividend payments on preferred stock. + References No definition available. + Details
Name: | us-gaap_PreferredStockDividendRatePerDollarAmount
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Value of the difference between preference in liquidation and the par or stated values of the preferred shares. + References No definition available. + Details
Name: | us-gaap_PreferredStockLiquidationPreferenceValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_PreferredStockSharesAuthorized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_PreferredStockSharesOutstanding
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Per share or per unit amount of equity securities issued. + References No definition available. + Details
Name: | us-gaap_SharesIssuedPricePerShare
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=us-gaap_CommonClassAMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=us-gaap_CommonClassBMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=us-gaap_ConvertiblePreferredStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=dbx_SeriesAConvertiblePreferredStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=dbx_SeriesA1ConvertiblePreferredStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=dbx_SeriesBConvertiblePreferredStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=dbx_SeriesCConvertiblePreferredStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConversionOfStockByUniqueDescriptionAxis=dbx_ConversionOfConvertiblePreferredStockToClassBCommonStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConversionOfStockByUniqueDescriptionAxis=dbx_ConversionOfConvertiblePreferredStockToClassACommonStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |