Revenue (Disaggregation of Revenue by Product) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue	$ 24,539.8	$ 22,319.5	$ 21,493.3
U.S.
Disaggregation of Revenue [Line Items]
Revenue	14,229.3	12,722.6	12,391.9
Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	10,310.5	9,596.8	9,101.4
Diabetes | U.S.
Disaggregation of Revenue [Line Items]
Revenue	7,909.1	7,529.5	6,607.0
Diabetes | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	3,925.3	3,602.6	3,212.5
Trulicity® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	3,835.9	3,155.2	2,515.8
Trulicity® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	1,232.2	972.7	683.3
Humalog® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	1,485.6	1,669.7	1,787.8
Humalog® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	1,140.3	1,151.0	1,208.7
Humulin® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	866.4	879.7	910.2
Humulin® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	393.2	410.4	421.2
Jardiance®
Disaggregation of Revenue [Line Items]
Revenue	1,153.8	944.2	658.3
Jardiance® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	620.8	565.9	400.2
Jardiance® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	533.0	378.3	258.1
Basaglar®
Disaggregation of Revenue [Line Items]
Revenue	1,124.4	1,112.6	801.2
Basaglar® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	842.3	876.2	622.8
Basaglar® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	282.1	236.3	178.5
Trajenta®
Disaggregation of Revenue [Line Items]
Revenue	358.5	590.6	574.7
Trajenta® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	95.6	224.8	224.2
Trajenta® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	263.0	365.8	350.5
Other Diabetes | U.S.
Disaggregation of Revenue [Line Items]
Revenue	162.5	158.0	146.0
Other Diabetes | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	81.5	88.1	112.2
Oncology | U.S.
Disaggregation of Revenue [Line Items]
Revenue	2,792.1	2,608.5	2,403.2
Oncology | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	2,527.2	2,005.9	1,857.3
Alimta® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	1,265.3	1,219.5	1,131.0
Alimta® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	1,064.7	896.4	1,001.9
Cyramza® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	381.9	335.3	291.5
Cyramza® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	650.8	589.9	529.9
Verzenio® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	618.2	454.8	248.5
Verzenio® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	294.4	124.9	6.6
Erbitux® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	480.1	487.9	531.6
Erbitux® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	56.3	55.4	103.8
Other Oncology | U.S.
Disaggregation of Revenue [Line Items]
Revenue	46.6	111.0	200.6
Other Oncology | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	461.0	339.3	215.1
Immunology | U.S.
Disaggregation of Revenue [Line Items]
Revenue	1,372.3	1,059.0	745.4
Immunology | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	1,089.6	734.3	394.6
Taltz® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	1,288.5	1,016.8	738.7
Taltz® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	500.0	349.6	198.7
Olumiant®
Disaggregation of Revenue [Line Items]
Revenue	638.9	426.9	202.5
Olumiant® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	63.8	42.2	6.7
Olumiant® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	575.0	384.7	195.9
Other Immunology | U.S.
Disaggregation of Revenue [Line Items]
Revenue	20.0	0.0	0.0
Other Immunology | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	14.6	0.0	0.0
Neuroscience | U.S.
Disaggregation of Revenue [Line Items]
Revenue	487.3	356.5	277.4
Neuroscience | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	1,344.0	1,366.4	1,543.3
Cymbalta® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	42.1	49.6	54.3
Cymbalta® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	725.6	675.8	653.7
Zyprexa® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	46.1	41.0	36.2
Zyprexa® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	360.5	377.6	435.1
Emgality® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	325.9	154.9	4.9
Emgality® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	37.0	7.7	0.0
Other Neuroscience | U.S.
Disaggregation of Revenue [Line Items]
Revenue	73.2	111.0	182.0
Other Neuroscience | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	220.9	305.3	454.5
Other | U.S.
Disaggregation of Revenue [Line Items]
Revenue	1,668.4	1,169.1	2,358.8
Other | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	1,424.4	1,887.7	2,093.7
Forteo® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	510.3	645.5	757.9
Forteo® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	536.0	759.1	817.7
Bamlanivimab
Disaggregation of Revenue [Line Items]
Revenue	871.2
Bamlanivimab | U.S.
Disaggregation of Revenue [Line Items]
Revenue	850.0	0.0	0.0
Bamlanivimab | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	21.2	0.0	0.0
Cialis® | U.S.
Disaggregation of Revenue [Line Items]
Revenue	61.8	231.7	1,129.2
Cialis® | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	545.4	658.8	722.7
Other | U.S.
Disaggregation of Revenue [Line Items]
Revenue	246.4	291.9	471.8
Other | Outside U.S.
Disaggregation of Revenue [Line Items]
Revenue	$ 321.8	$ 469.7	$ 553.3