Revenue (Disaggregation of Revenue by Product) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 5,499.4	$ 5,636.7	$ 11,359.2	$ 10,728.9
U.S.
Disaggregation of Revenue [Line Items]
Revenue	3,144.8	3,252.5	6,473.6	6,143.3
Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	2,354.6	2,384.2	4,885.6	4,585.6
Diabetes
Disaggregation of Revenue [Line Items]
Revenue	2,779.0	2,762.3	5,747.9	5,315.3
Diabetes | U.S.
Disaggregation of Revenue [Line Items]
Revenue	1,873.3	1,882.8	3,864.5	3,602.2
Diabetes | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	905.7	879.5	1,883.4	1,713.1
Trulicity®
Disaggregation of Revenue [Line Items]
Revenue	1,229.8	1,028.5	2,459.1	1,908.3
Trulicity® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	952.5	792.1	1,882.0	1,457.7
Trulicity® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	277.2	236.4	577.1	450.6
Humalog®
Disaggregation of Revenue [Line Items]
Revenue	555.1	677.6	1,250.8	1,408.4
Humalog® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	281.7	396.1	680.3	844.8
Humalog® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	273.3	281.5	570.5	563.7
Humulin®
Disaggregation of Revenue [Line Items]
Revenue	313.6	322.6	629.3	620.3
Humulin® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	214.3	220.1	428.4	421.3
Humulin® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	99.3	102.6	200.8	199.0
Basaglar®
Disaggregation of Revenue [Line Items]
Revenue	290.4	290.7	594.1	542.1
Basaglar® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	229.7	232.2	460.1	430.3
Basaglar® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	60.7	58.6	134.0	111.8
Jardiance
Disaggregation of Revenue [Line Items]
Revenue	262.0	231.9	529.5	435.5
Jardiance | U.S.
Disaggregation of Revenue [Line Items]
Revenue	145.1	142.6	289.7	267.8
Jardiance | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	116.9	89.3	239.8	167.7
Trajenta
Disaggregation of Revenue [Line Items]
Revenue	76.8	153.9	170.0	285.9
Trajenta | U.S.
Disaggregation of Revenue [Line Items]
Revenue	16.4	64.5	45.1	111.8
Trajenta | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	60.5	89.5	124.9	174.0
Other Diabetes
Disaggregation of Revenue [Line Items]
Revenue	51.3	57.1	115.1	114.8
Other Diabetes | U.S.
Disaggregation of Revenue [Line Items]
Revenue	33.6	35.2	78.9	68.5
Other Diabetes | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	17.8	21.6	36.3	46.3
Oncology
Disaggregation of Revenue [Line Items]
Revenue	1,268.6	1,197.2	2,470.1	2,210.0
Oncology | U.S.
Disaggregation of Revenue [Line Items]
Revenue	682.7	689.8	1,340.6	1,283.7
Oncology | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	585.9	507.4	1,129.5	926.3
Alimta®
Disaggregation of Revenue [Line Items]
Revenue	539.1	577.8	1,099.2	1,076.9
Alimta® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	317.2	341.7	641.5	623.5
Alimta® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	221.9	236.1	457.7	453.5
Cyramza®
Disaggregation of Revenue [Line Items]
Revenue	256.7	241.8	495.7	440.0
Cyramza® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	94.1	89.8	183.2	164.9
Cyramza® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	162.7	152.0	312.5	275.2
Verzenio®
Disaggregation of Revenue [Line Items]
Revenue	208.6	133.9	396.7	243.3
Verzenio® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	141.7	105.2	271.1	198.7
Verzenio® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	66.9	28.7	125.6	44.6
Erbitux®
Disaggregation of Revenue [Line Items]
Revenue	129.5	159.3	260.3	277.7
Erbitux® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	115.8	136.9	233.7	250.3
Erbitux® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	13.7	22.4	26.7	27.5
Other Oncology
Disaggregation of Revenue [Line Items]
Revenue	134.7	84.4	218.2	172.1
Other Oncology | U.S.
Disaggregation of Revenue [Line Items]
Revenue	13.9	16.2	11.1	46.3
Other Oncology | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	120.7	68.2	207.0	125.5
Immunology
Disaggregation of Revenue [Line Items]
Revenue	548.3	456.1	1,134.1	790.8
Immunology | U.S.
Disaggregation of Revenue [Line Items]
Revenue	310.5	278.8	651.9	466.0
Immunology | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	237.8	177.3	482.2	324.8
Taltz®
Disaggregation of Revenue [Line Items]
Revenue	395.2	353.8	838.7	606.3
Taltz® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	289.2	268.1	616.7	449.0
Taltz® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	106.0	85.7	222.0	157.4
Olumiant®
Disaggregation of Revenue [Line Items]
Revenue	145.0	102.4	284.7	184.5
Olumiant® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	13.2	10.7	24.5	17.1
Olumiant® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	131.8	91.7	260.2	167.4
Other Immunology
Disaggregation of Revenue [Line Items]
Revenue	8.1	0.0	10.7	0.0
Other Immunology | U.S.
Disaggregation of Revenue [Line Items]
Revenue	8.1	0.0	10.7	0.0
Other Immunology | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	0.0	0.0	0.0	0.0
Neuroscience
Disaggregation of Revenue [Line Items]
Revenue	422.5	452.7	886.0	845.9
Neuroscience | U.S.
Disaggregation of Revenue [Line Items]
Revenue	104.0	104.4	214.2	155.5
Neuroscience | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	318.5	348.3	671.7	690.3
Cymbalta®
Disaggregation of Revenue [Line Items]
Revenue	179.9	187.2	390.3	351.3
Cymbalta® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	7.7	18.1	19.3	28.4
Cymbalta® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	172.1	169.0	370.9	322.9
Zyprexa®
Disaggregation of Revenue [Line Items]
Revenue	96.6	104.3	195.0	211.5
Zyprexa® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	9.1	9.3	20.3	18.6
Zyprexa® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	87.5	95.1	174.7	193.0
Emgality®
Disaggregation of Revenue [Line Items]
Revenue	87.4	34.3	161.5	48.5
Emgality® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	80.6	33.8	147.9	46.0
Emgality® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	6.8	0.5	13.6	2.6
Other Neuroscience
Disaggregation of Revenue [Line Items]
Revenue	58.6	126.9	139.2	234.6
Other Neuroscience | U.S.
Disaggregation of Revenue [Line Items]
Revenue	6.6	43.2	26.7	62.5
Other Neuroscience | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	52.1	83.7	112.5	171.8
Other
Disaggregation of Revenue [Line Items]
Revenue	481.0	768.4	1,121.1	1,567.0
Other | U.S.
Disaggregation of Revenue [Line Items]
Revenue	174.4	296.7	402.4	635.9
Other | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	306.7	471.7	718.7	931.2
Forteo®
Disaggregation of Revenue [Line Items]
Revenue	252.7	360.8	525.0	673.7
Forteo® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	119.6	172.8	242.2	298.7
Forteo® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	133.0	188.0	282.9	375.0
Cialis®
Disaggregation of Revenue [Line Items]
Revenue	130.7	200.2	323.8	508.4
Cialis® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	23.4	35.1	49.5	178.4
Cialis® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	107.3	165.1	274.3	330.0
Other
Disaggregation of Revenue [Line Items]
Revenue	97.6	207.4	272.3	384.9
Other | U.S.
Disaggregation of Revenue [Line Items]
Revenue	31.4	88.8	110.7	158.8
Other | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	$ 66.4	$ 118.6	$ 161.5	$ 226.2