Revenue (Disaggregation of Revenue by Product) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Revenue	$ 5,636.7	$ 5,585.0	$ 10,728.9	$ 10,548.8
U.S.
Disaggregation of Revenue [Line Items]
Revenue	3,252.5	3,242.3	6,143.3	6,037.9
Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	2,384.2	2,342.7	4,585.6	4,510.9
Endocrinology
Disaggregation of Revenue [Line Items]
Revenue	3,207.2	2,954.9	6,137.3	5,653.7
Endocrinology | U.S.
Disaggregation of Revenue [Line Items]
Revenue	2,102.0	1,901.2	3,975.9	3,617.0
Endocrinology | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	1,105.2	1,053.8	2,161.4	2,036.6
Trulicity®
Disaggregation of Revenue [Line Items]
Revenue	1,028.5	779.8	1,908.3	1,458.1
Trulicity® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	792.1	612.4	1,457.7	1,140.6
Trulicity® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	236.4	167.4	450.6	317.5
Humalog®
Disaggregation of Revenue [Line Items]
Revenue	677.6	769.8	1,408.4	1,561.5
Humalog® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	396.1	464.5	844.8	968.7
Humalog® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	281.5	305.2	563.7	592.8
Forteo®
Disaggregation of Revenue [Line Items]
Revenue	360.8	434.5	673.7	747.8
Forteo® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	172.8	225.1	298.7	347.2
Forteo® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	188.0	209.4	375.0	400.5
Humulin®
Disaggregation of Revenue [Line Items]
Revenue	322.6	346.0	620.3	671.9
Humulin® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	220.1	238.8	421.3	460.4
Humulin® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	102.6	107.2	199.0	211.5
Basaglar®
Disaggregation of Revenue [Line Items]
Revenue	290.7	201.8	542.1	367.8
Basaglar® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	232.2	156.5	430.3	283.2
Basaglar® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	58.6	45.3	111.8	84.6
Jardiance
Disaggregation of Revenue [Line Items]
Revenue	231.9	147.2	435.5	298.2
Jardiance | U.S.
Disaggregation of Revenue [Line Items]
Revenue	142.6	85.6	267.8	180.6
Jardiance | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	89.3	61.6	167.7	117.6
Trajenta
Disaggregation of Revenue [Line Items]
Revenue	153.9	141.7	285.9	282.8
Trajenta | U.S.
Disaggregation of Revenue [Line Items]
Revenue	64.5	56.8	111.8	110.9
Trajenta | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	89.5	84.9	174.0	171.9
Other Endocrinology
Disaggregation of Revenue [Line Items]
Revenue	141.2	134.1	263.1	265.6
Other Endocrinology | U.S.
Disaggregation of Revenue [Line Items]
Revenue	81.6	61.5	143.5	125.4
Other Endocrinology | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	59.3	72.8	119.6	140.2
Oncology
Disaggregation of Revenue [Line Items]
Revenue	1,197.2	1,110.1	2,210.0	2,066.7
Oncology | U.S.
Disaggregation of Revenue [Line Items]
Revenue	689.8	611.1	1,283.7	1,121.4
Oncology | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	507.4	499.0	926.3	945.3
Alimta®
Disaggregation of Revenue [Line Items]
Revenue	577.8	555.9	1,076.9	1,055.5
Alimta® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	341.7	281.3	623.5	526.7
Alimta® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	236.1	274.6	453.5	528.9
Cyramza®
Disaggregation of Revenue [Line Items]
Revenue	241.8	218.8	440.0	402.4
Cyramza® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	89.8	75.4	164.9	143.7
Cyramza® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	152.0	143.3	275.2	258.7
Erbitux®
Disaggregation of Revenue [Line Items]
Revenue	159.3	166.4	277.7	316.1
Erbitux® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	136.9	140.0	250.3	261.3
Erbitux® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	22.4	26.4	27.5	54.7
Verzenio®
Disaggregation of Revenue [Line Items]
Revenue	133.9	57.7	243.3	87.4
Verzenio® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	105.2	57.7	198.7	87.4
Verzenio® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	28.7	0.0	44.6	0.0
Other Oncology
Disaggregation of Revenue [Line Items]
Revenue	84.4	111.3	172.1	205.3
Other Oncology | U.S.
Disaggregation of Revenue [Line Items]
Revenue	16.2	56.7	46.3	102.3
Other Oncology | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	68.2	54.7	125.5	103.0
Neuroscience
Disaggregation of Revenue [Line Items]
Revenue	452.7	471.0	845.9	943.7
Neuroscience | U.S.
Disaggregation of Revenue [Line Items]
Revenue	104.4	65.6	155.5	157.8
Neuroscience | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	348.3	405.3	690.3	785.9
Cymbalta®
Disaggregation of Revenue [Line Items]
Revenue	187.2	181.9	351.3	351.5
Cymbalta® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	18.1	12.6	28.4	24.8
Cymbalta® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	169.0	169.4	322.9	326.7
Zyprexa®
Disaggregation of Revenue [Line Items]
Revenue	104.3	128.0	211.5	250.6
Zyprexa® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	9.3	11.8	18.6	20.6
Zyprexa® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	95.1	116.2	193.0	230.0
Strattera®
Disaggregation of Revenue [Line Items]
Revenue	82.6	114.2	148.8	244.9
Strattera® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	21.2	16.9	22.7	63.9
Strattera® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	61.4	97.3	126.1	181.0
Emgality®
Disaggregation of Revenue [Line Items]
Revenue	34.3	0.0	48.5	0.0
Emgality® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	33.8	0.0	46.0	0.0
Emgality® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	0.5	0.0	2.6	0.0
Other Neuroscience
Disaggregation of Revenue [Line Items]
Revenue	44.3	46.9	85.8	96.7
Other Neuroscience | U.S.
Disaggregation of Revenue [Line Items]
Revenue	22.0	24.3	39.8	48.5
Other Neuroscience | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	22.3	22.4	45.7	48.2
Immunology
Disaggregation of Revenue [Line Items]
Revenue	456.1	264.7	790.8	443.4
Immunology | U.S.
Disaggregation of Revenue [Line Items]
Revenue	278.8	175.3	466.0	286.5
Immunology | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	177.3	89.4	324.8	157.0
Taltz®
Disaggregation of Revenue [Line Items]
Revenue	353.8	220.1	606.3	366.5
Taltz® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	268.1	173.6	449.0	284.7
Taltz® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	85.7	46.5	157.4	81.8
Olumiant®
Disaggregation of Revenue [Line Items]
Revenue	102.4	44.7	184.5	76.9
Olumiant® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	10.7	1.7	17.1	1.7
Olumiant® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	91.7	42.9	167.4	75.2
Other
Disaggregation of Revenue [Line Items]
Revenue	323.5	784.3	744.9	1,441.3
Other | U.S.
Disaggregation of Revenue [Line Items]
Revenue	77.5	489.1	262.2	855.2
Other | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	245.9	295.2	482.9	586.1
Cialis®
Disaggregation of Revenue [Line Items]
Revenue	200.2	538.7	508.4	1,034.1
Cialis® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	35.1	345.7	178.4	659.1
Cialis® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	165.1	193.0	330.0	375.0
Other
Disaggregation of Revenue [Line Items]
Revenue	123.3	245.6	236.5	407.2
Other | U.S.
Disaggregation of Revenue [Line Items]
Revenue	42.4	143.4	83.8	196.1
Other | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	$ 80.8	$ 102.2	$ 152.8	$ 211.1