XML 74 R36.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Earnings per Share (Tables) | 3 Months Ended
--- | ---
Mar. 31, 2018
Earnings Per Share [Abstract] |
Basic and diluted earnings per share | Basic and diluted earnings per share are calculated as follows:
| For the Three Months Ended March 31,
(In millions) | 2018 |  | 2017
Numerator: |  |  |
Net income attributable to Biogen Inc. | $ | 1,172.9 |  |  | $ | 747.6 |
Denominator: |  |  |
Weighted-average number of common shares outstanding | 211.4 |  |  | 215.6 |
Effect of dilutive securities: |  |  |
Stock options and employee stock purchase plan | — |  |  | — |
Time-vested restricted stock units | 0.2 |  |  | 0.2 |
Market stock units | 0.1 |  |  | 0.1 |
Performance stock units settled in stock | — |  |  | — |
Dilutive potential common shares | 0.3 |  |  | 0.3 |
Shares used in calculating diluted earnings per share | 211.7 |  |  | 215.9 |

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

X
- Definition Tabular disclosure of an entity's basic and diluted earnings per share calculations, including a reconciliation of numerators and denominators of the basic and diluted per-share computations for income from continuing operations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 + Details
Name: | us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration