Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Statement [Abstract]
Net revenues	$ 2,867.4	$ 2,719.9	$ 2,854.0
Cost of goods sold	1,662.5	1,541.1	1,601.7
Selling and administrative expenses	674.7	635.7	681.3
Impairment of goodwill and intangible assets	0.0	101.7	5.9
Loss on assets held for sale	0.0	37.9	0.0
Operating income	530.2	403.5	565.1
Interest expense	50.2	51.1	56.0
Loss on divestitures	0.0	0.0	30.1
Other (income) expense, net	(44.0)	(13.0)	3.8
Earnings before income taxes	524.0	365.4	475.2
Provision for income taxes	40.7	50.9	73.1
Net earnings	483.3	314.5	402.1
Less: Net earnings attributable to noncontrolling interests	0.3	0.2	0.3
Net earnings attributable to Allegion plc	483.0	314.3	401.8
Currency translation	(63.3)	57.3	13.4
Unrealized net gains arising during period	2.6	3.9	0.0
Net gains reclassified into earnings	(0.2)	(5.8)	(7.5)
Tax (expense) benefit	(0.6)	0.5	1.9
Total cash flow hedges, net of tax	1.8	(1.4)	(5.6)
Prior service gains (costs) and net actuarial gains (losses), net	25.7	4.9	(8.3)
Amortization reclassified into earnings	4.8	5.0	6.1
Settlements/curtailments reclassified into earnings	0.5	0.1	2.3
Currency translation and other	1.0	(2.1)	(2.7)
Tax expense	(7.7)	(2.0)	(0.4)
Total pension and OPEB adjustments, net of tax	24.3	5.9	(3.0)
Other comprehensive (loss) income, net of tax	(37.2)	61.8	4.8
Total comprehensive income, net of tax	446.1	376.3	406.9
Less: Total comprehensive income attributable to noncontrolling interests	0.4	0.5	0.2
Total comprehensive income attributable to Allegion plc	$ 445.7	$ 375.8	$ 406.7
Basic:
Net earnings	$ 5.37	$ 3.41	$ 4.29
Diluted:
Net earnings	$ 5.34	$ 3.39	$ 4.26