Business Segments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Net revenues:	$ 1,305.0	$ 1,330.3	$ 2,655.7	$ 2,617.5
Percent change in net revenues	(1.90%)		1.50%
Gross profit:	$ 843.7	850.0	$ 1,700.5	1,660.6
Percent change in gross profit	(0.70%)		2.40%
Operating profit	$ 383.9	415.1	$ 777.5	800.0
Percent change in operating profit	(7.50%)		(2.80%)
Long-lived assets:	$ 193.0	185.4	$ 193.0	185.4
Percent change in long-lived assets	4.10%
Corporate
Segment Reporting Information [Line Items]
Unallocated corporate general and administrative expenses	$ 50.3	46.7	94.7	85.2
Application Software
Segment Reporting Information [Line Items]
Net revenues:	$ 398.4	390.6	$ 803.5	771.8
Percent change in net revenues	2.00%		4.10%
Gross profit:	$ 273.8	262.7	$ 544.2	516.1
Percent change in gross profit	4.20%		5.40%
Operating profit	$ 113.4	98.4	$ 211.0	189.8
Percent change in operating profit	15.20%		11.20%
Long-lived assets:	$ 88.5	83.3	$ 88.5	83.3
Percent change in long-lived assets	6.20%
Network Software & Systems
Segment Reporting Information [Line Items]
Net revenues:	$ 422.0	366.8	$ 860.2	712.5
Percent change in net revenues	15.00%		20.70%
Gross profit:	$ 284.8	252.7	$ 578.0	491.7
Percent change in gross profit	12.70%		17.60%
Operating profit	$ 130.6	129.2	$ 269.3	254.5
Percent change in operating profit	1.10%		5.80%
Long-lived assets:	$ 46.5	38.6	$ 46.5	38.6
Percent change in long-lived assets	20.50%
Measurement & Analytical Solutions
Segment Reporting Information [Line Items]
Net revenues:	$ 363.9	408.4	$ 729.1	810.2
Percent change in net revenues	(10.90%)		(10.00%)
Gross profit:	$ 221.5	240.2	$ 436.1	471.4
Percent change in gross profit	(7.80%)		(7.50%)
Operating profit	$ 123.0	130.3	$ 237.0	248.4
Percent change in operating profit	(5.60%)		(4.60%)
Long-lived assets:	$ 37.4	41.7	$ 37.4	41.7
Percent change in long-lived assets	(10.30%)
Process Technologies
Segment Reporting Information [Line Items]
Net revenues:	$ 120.7	164.5	$ 262.9	323.0
Percent change in net revenues	(26.60%)		(18.60%)
Gross profit:	$ 63.6	94.4	$ 142.2	181.4
Percent change in gross profit	(32.60%)		(21.60%)
Operating profit	$ 16.9	57.2	$ 60.2	107.3
Percent change in operating profit	(70.50%)		(43.90%)
Long-lived assets:	$ 20.6	$ 21.8	$ 20.6	$ 21.8
Percent change in long-lived assets	(5.50%)