Revenue - Disaggregation of Revenue (Details) - USD ($) $ 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
Disaggregation of Revenue [Line Items]
Net sales	$ 1,305.5	$ 1,162.0	$ 1,005.7	$ 897.3	$ 1,171.5	$ 1,070.7	$ 1,134.1	$ 1,054.8	$ 4,370.6	$ 4,431.2	$ 4,285.6
Products and services transferred at a point in time
Disaggregation of Revenue [Line Items]
Net sales									3,249.3	3,348.4	3,205.9
Products and services transferred over time
Disaggregation of Revenue [Line Items]
Net sales									1,121.3	1,082.8	1,079.7
Critical infrastructure & solutions
Disaggregation of Revenue [Line Items]
Net sales									2,457.7	2,467.5	2,301.1
Critical infrastructure & solutions | Restatement Adjustment
Disaggregation of Revenue [Line Items]
Net sales										(165.1)	(150.7)
Services & spares
Disaggregation of Revenue [Line Items]
Net sales									1,324.8	1,338.1	1,305.3
Services & spares | Restatement Adjustment
Disaggregation of Revenue [Line Items]
Net sales										39.2	29.2
Integrated rack solutions
Disaggregation of Revenue [Line Items]
Net sales									588.1	625.6	679.2
Integrated rack solutions | Restatement Adjustment
Disaggregation of Revenue [Line Items]
Net sales										125.9	121.5
Americas
Disaggregation of Revenue [Line Items]
Net sales									2,040.6	2,229.1	2,145.7
Americas | Products and services transferred at a point in time
Disaggregation of Revenue [Line Items]
Net sales									1,418.9	1,592.4	1,530.6
Americas | Products and services transferred over time
Disaggregation of Revenue [Line Items]
Net sales									621.7	636.7	615.1
Americas | Critical infrastructure & solutions
Disaggregation of Revenue [Line Items]
Net sales									1,074.2	1,225.6	1,118.8
Americas | Services & spares
Disaggregation of Revenue [Line Items]
Net sales									662.6	689.8	689.9
Americas | Integrated rack solutions
Disaggregation of Revenue [Line Items]
Net sales									303.8	313.7	337.0
Asia Pacific
Disaggregation of Revenue [Line Items]
Net sales									1,368.4	1,278.0	1,244.2
Asia Pacific | Products and services transferred at a point in time
Disaggregation of Revenue [Line Items]
Net sales									1,078.5	1,007.1	973.5
Asia Pacific | Products and services transferred over time
Disaggregation of Revenue [Line Items]
Net sales									289.9	270.9	270.7
Asia Pacific | Critical infrastructure & solutions
Disaggregation of Revenue [Line Items]
Net sales									853.8	755.5	729.1
Asia Pacific | Services & spares
Disaggregation of Revenue [Line Items]
Net sales									371.1	361.1	344.2
Asia Pacific | Integrated rack solutions
Disaggregation of Revenue [Line Items]
Net sales									143.5	161.4	170.9
Europe, Middle East, & Africa
Disaggregation of Revenue [Line Items]
Net sales									961.6	924.1	895.7
Europe, Middle East, & Africa | Products and services transferred at a point in time
Disaggregation of Revenue [Line Items]
Net sales									751.9	748.9	701.8
Europe, Middle East, & Africa | Products and services transferred over time
Disaggregation of Revenue [Line Items]
Net sales									209.7	175.2	193.9
Europe, Middle East, & Africa | Critical infrastructure & solutions
Disaggregation of Revenue [Line Items]
Net sales									529.7	486.4	453.2
Europe, Middle East, & Africa | Services & spares
Disaggregation of Revenue [Line Items]
Net sales									291.1	287.2	271.2
Europe, Middle East, & Africa | Integrated rack solutions
Disaggregation of Revenue [Line Items]
Net sales									$ 140.8	$ 150.5	$ 171.3