Pay vs Performance Disclosure - USD ($)

12 Months Ended

Dec. 31, 2022

Dec. 31, 2021

Dec. 31, 2020

Pay vs Performance Disclosure [Table]

Pay versus Performance Comparison

As discussed in our CD&A above, our CMDC has implemented executive compensation programs designed to link a substantial part of our NEOs compensation to financial, strategic, and market-based measures and align realizable compensation with stockholder return. The following table sets forth additional compensation information for our NEOs, calculated in accordance with SEC regulations, for fiscal years 2022, 2021 and 2020.

Pay versus Performance Tabular Disclosure: The table below contains information about the relationship between compensation actually paid, as computed in accordance with SEC rules, to our CEO and

non-CEO

NEOs as a group ,and our financial performance for the three years 2020 – 2022. The cumulative Total Stockholder Return depicts a

hypothetical $100 investment in our common stock on December 31, 2019, and shows the value of that investment over time for each calendar year. A hypothetical $100 investment in the NASDAQ Biotech Index using the same methodology is shown for comparison.

The CMDC did not consider the pay versus performance disclosure below in making its pay decisions for any of the fiscal years shown. In addition, the average

non-CEO

NEO incumbents differ year to year and may comprise different roles with different individual and market-based considerations impacting compensation decisions. Comparing the summary compensation table total average and compensation actually paid average for the

non-CEO

NEOs year over year does not accurately depict changes in these values for the same individuals.



Fiscal Year	SCT Total for CEO: C. Viehbacher (1)		SCT Total for Former CEO: M. Vounatsos (1)		Compensation Actually Paid to CEO (2)		Compensation Actually Paid to Former CEO (2)		Average SCT Total for Other NEOs		Average Compensation Actually Paid for Other NEOs (2)(3)		Value of $100 Initial Fixed Investment Based on TSR		Value of $100 Initial Fixed Investment Based on NASDAQ Biotech Index TSR (4)		Net Income ($M)		Company Selected Measure: Revenue (5)
2022	$	30,488,593	$	26,625,221	$	27,551,849	$	5,898,711	$	5,878,461	$	4,969,471	$	93.32	$	111.27	$	3,047	$	10,326M
2021		—	$	17,689,665		—	$	15,211,025	$	5,761,560	$	5,081,941	$	80.85	$	124.89	$	1,556	$	11,054M
2020		—	$	18,659,829		—	$	8,578,367	$	6,525,375	$	4,363,675	$	82.52	$	125.69	$	4,001	$	13,952M

Notes to Pay Vs. Performance Table

(1)

The dollar amounts reported are the amounts of total compensation reported for our CEO, Mr. Viehbacher, and our former CEO, Mr. Vounatsos in the Summary Compensation Table for fiscal years 2022, 2021 and 2020. Mr. Vounatsos served as CEO for each of the full fiscal years 2021 and 2020, while Mr. Viehbacher and Mr. Vounatsos both served as CEO in fiscal year 2022.

(2)

The dollar amounts reported represent the amount of “compensation actually paid”, as computed in accordance with SEC rules. The dollar amounts do not reflect the actual amounts of compensation paid to our CEO and other NEOs during the applicable year, but also include (i) the

year-end

fair value of equity awards granted during the reported year, (ii) the change in fair value of equity awards that were unvested at the end of the prior year, measured through the date the awards vested or were forfeited, or through the end of the reported fiscal year.

(3)

For 2022, reflects compensation information for our NEOs, other than our CEO, as described in the CD&A of this proxy statement. For 2021, reflects compensation information for Mr. McDonnell, Ms. Alexander, Mr. Guindo and Alfred Sandrock, our former EVP of R&D. For 2020, reflects compensation information for Mr. McDonnell, Ms. Alexander, Mr. Guindo, Dr. Sandrock and Jeffrey Capello, our former CFO.

(4)

Reflects cumulative total stockholder return of the NASDAQ Biotechnology Index (NBI) as of December 31, 2022. The NBI is the peer group used by BIIB for the purposes of item 201(e) of Regulation

S-K

under the Exchange Act in the Company’s Annual Report on Form

10-K

for the year ended December 31, 2022.

(5)	Revenue was adjusted to neutralize the effects of foreign exchange rate fluctuations.

The following tables set forth the adjustments made during each year in the PVP table to arrive at “compensation actually paid” to our Principal Executive Officer during each year.



Fiscal Year	Summary Compensation Table Total for CEO		Summary Compensation Table Total for former CEO		Reported Value of Equity Awards for CEO (1)		Reported Value of Equity Awards for former CEO (1)		Equity Award Adjustments for CEO (2)		Equity Award Adjustments for former CEO (2)		Compensation Actually Paid to CEO		Compensation Actually Paid to former CEO
2022	$	30,488,593	$	26,625,221	$	30,000,655	$	15,389,732	$	27,063,911	-$	5,336,778	$	27,551,849	$	5,898,711
2021		—	$	17,689,665		—	$	14,084,314		—	$	11,605,674		—	$	15,211,025
2020		—	$	18,659,829		—	$	13,887,064		—	$	3,805,602		—	$	8,578,367

(1)	Represents the grant date fair value of equity awards to our CEO and former CEO, as reported in the “Stock Awards” and “Option Awards” columns in the Summary Compensation Table for each applicable year.

(2)	Represents the year-over-year change in the fair value of equity awards to our CEO and former CEO, as itemized in the table below. No awards vested in the year they were granted.



	2022

Fair Value of Equity Awards for CEO and former CEO	Mr. Viehbacher		Mr. Vounatsos		2021		2020
As of year-end for awards granted during the year	$	27,063,911	$	1,996,870	$	10,985,776	$	8,893,002
Year-over-year increase or decrease of unvested awards granted in prior years	$	0	-$	6,247,880	-$	687,744	-$	3,618,885
Increase or decrease from prior fiscal year-end for awards that vested during the year	$	0	-$	1,085,768	$	1,307,643	-$	1,468,515
Total Equity Award Adjustments	$	27,063,911	-$	5,336,778	$	11,605,674	$	3,805,602

The following tables set forth the adjustments made during each year in the PVP table to arrive at “compensation actually paid” to our

non-CEO

NEOs during each year.



Fiscal Year	Average Summary Compensation Table Total for Non-CEO NEOs		Average Reported Value of Equity Awards for non-CEO NEOs (1)		Average Equity Award Adjustments for non-CEO NEOs (2)		Average Compensation Actually Paid to non-CEO NEOs
2022	$	5,878,461	$	4,223,226	$	3,314,236	$	4,969,471
2021	$	5,761,560	$	4,105,942	$	3,426,323	$	5,081,941
2020	$	6,525,375	$	4,158,006	$	1,996,306	$	4,363,675

(1)	Represents the average of the grant date fair value of the equity awards to our named executive officers (other than our CEO and former CEO), as reported in the “Stock Awards” column in the SCT for each applicable year.

(2)	Represents the average of the year-over-year change in fair value of equity awards to our named executive officers (other than our CEO and former CEO), as itemized in the table below. No awards vested in the year they were granted.



Average Fair Value of Equity Awards for non-CEO NEOs	2022		2021		2020
As of year-end for awards granted during the year	$	3,809,706	$	3,295,987	$	2,904,843
Year-over-year increase or decrease of unvested awards granted in prior years	-$	244,173	-$	156,359	-$	741,018
Increase or decrease from prior fiscal year-end for awards that vested during the year	-$	251,296	$	286,695	-$	167,520
Total Equity Award Adjustments	$	3,314,236	$	3,426,323	$	1,996,306

Company Selected Measure Name

Revenue

Named Executive Officers, Footnote [Text Block]

Peer Group Issuers, Footnote [Text Block]

Reflects cumulative total stockholder return of the NASDAQ Biotechnology Index (NBI) as of December 31, 2022. The NBI is the peer group used by BIIB for the purposes of item 201(e) of Regulation

S-K

under the Exchange Act in the Company’s Annual Report on Form

10-K

for the year ended December 31, 2022.

Adjustment To PEO Compensation, Footnote [Text Block]

The following tables set forth the adjustments made during each year in the PVP table to arrive at “compensation actually paid” to our Principal Executive Officer during each year.



Fiscal Year	Summary Compensation Table Total for CEO		Summary Compensation Table Total for former CEO		Reported Value of Equity Awards for CEO (1)		Reported Value of Equity Awards for former CEO (1)		Equity Award Adjustments for CEO (2)		Equity Award Adjustments for former CEO (2)		Compensation Actually Paid to CEO		Compensation Actually Paid to former CEO
2022	$	30,488,593	$	26,625,221	$	30,000,655	$	15,389,732	$	27,063,911	-$	5,336,778	$	27,551,849	$	5,898,711
2021		—	$	17,689,665		—	$	14,084,314		—	$	11,605,674		—	$	15,211,025
2020		—	$	18,659,829		—	$	13,887,064		—	$	3,805,602		—	$	8,578,367

(1)	Represents the grant date fair value of equity awards to our CEO and former CEO, as reported in the “Stock Awards” and “Option Awards” columns in the Summary Compensation Table for each applicable year.

(2)	Represents the year-over-year change in the fair value of equity awards to our CEO and former CEO, as itemized in the table below. No awards vested in the year they were granted.



	2022

Fair Value of Equity Awards for CEO and former CEO	Mr. Viehbacher		Mr. Vounatsos		2021		2020
As of year-end for awards granted during the year	$	27,063,911	$	1,996,870	$	10,985,776	$	8,893,002
Year-over-year increase or decrease of unvested awards granted in prior years	$	0	-$	6,247,880	-$	687,744	-$	3,618,885
Increase or decrease from prior fiscal year-end for awards that vested during the year	$	0	-$	1,085,768	$	1,307,643	-$	1,468,515
Total Equity Award Adjustments	$	27,063,911	-$	5,336,778	$	11,605,674	$	3,805,602

Non-PEO NEO Average Total Compensation Amount

$ 5,878,461

$ 5,761,560

$ 6,525,375

Non-PEO NEO Average Compensation Actually Paid Amount

$ 4,969,471

5,081,941

4,363,675

Adjustment to Non-PEO NEO Compensation Footnote [Text Block]

The following tables set forth the adjustments made during each year in the PVP table to arrive at “compensation actually paid” to our

non-CEO

NEOs during each year.



Fiscal Year	Average Summary Compensation Table Total for Non-CEO NEOs		Average Reported Value of Equity Awards for non-CEO NEOs (1)		Average Equity Award Adjustments for non-CEO NEOs (2)		Average Compensation Actually Paid to non-CEO NEOs
2022	$	5,878,461	$	4,223,226	$	3,314,236	$	4,969,471
2021	$	5,761,560	$	4,105,942	$	3,426,323	$	5,081,941
2020	$	6,525,375	$	4,158,006	$	1,996,306	$	4,363,675

(1)	Represents the average of the grant date fair value of the equity awards to our named executive officers (other than our CEO and former CEO), as reported in the “Stock Awards” column in the SCT for each applicable year.

(2)	Represents the average of the year-over-year change in fair value of equity awards to our named executive officers (other than our CEO and former CEO), as itemized in the table below. No awards vested in the year they were granted.



Average Fair Value of Equity Awards for non-CEO NEOs	2022		2021		2020
As of year-end for awards granted during the year	$	3,809,706	$	3,295,987	$	2,904,843
Year-over-year increase or decrease of unvested awards granted in prior years	-$	244,173	-$	156,359	-$	741,018
Increase or decrease from prior fiscal year-end for awards that vested during the year	-$	251,296	$	286,695	-$	167,520
Total Equity Award Adjustments	$	3,314,236	$	3,426,323	$	1,996,306