Selected Quarterly Financial Data (Unaudited), Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Selected Quarterly Financial Data (Unaudited)
Excess tax benefit from option exercises	$ 14.8	$ 10.7	$ 12.4	$ 5.0	$ 16.8	$ 1.6	$ 12.9	$ 6.8	$ 42.8	$ 38.1	$ 19.8
Discrete income tax benefit, tax on foreign income				$ 19.9
Discrete income tax benefit, tax on foreign income, earnings per share				$ 0.06
Acquisition-related expenses	11.5						8.9	16.5	11.5	25.4	8.5
Acquisition-related expenses, net of tax	$ 10.7						$ 7.8	$ 13.2	10.7	21.0	7.2
Excess tax benefits related to stock-based compensation ( in dollars per share)	$ 0.05			$ 0.02		$ 0.01	$ 0.04	$ 0.02
Gain (loss) on extinguishment of debt						$ (14.3)			$ 0.0	(14.3)	0.0
Gain (loss) on extinguishment of debt, after tax						$ (12.5)				$ (12.5)
Gain (loss) on extinguishment of debt, per diluted share						$ (0.04)				$ (0.04)
Net income (loss) per common share-Diluted, acquisition-related expenses (in dollars per share)	$ (0.03)						$ (0.03)	$ (0.04)
Income tax expense (benefit)											$ (14.5)
Operating income (loss), aggregate effect	$ (11.5)						$ (8.9)	$ (16.5)
Net income, aggregate effect	4.1	10.7	12.4	$ 24.9	16.8	$ (10.9)	5.1	(6.4)
Net income attributable to Amphenol Corporation shareholders, aggregate effect	$ 4.1	$ 10.7	$ 12.4	$ 24.9	$ 16.8	$ (10.9)	$ 5.1	$ (6.4)
Earnings per share - diluted, aggregate effect (in dollars per share)	$ 0.02	$ 0.03	$ 0.04	$ 0.08	$ 0.05	$ (0.03)	$ 0.01	$ (0.02)