Condensed and Consolidated Statement of Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net cash provided by (used in) operating activities	$ 488.2	$ 457.8	$ 347.2
Cash flows from investing activities:
Capital expenditures	(65.6)	(49.1)	(49.3)
Acquisition of and equity investments in businesses, net of cash acquired	(7.6)	(376.1)	(20.8)
Proceeds from sale of property, plant and equipment			3.1
Purchase of investments	0.0	(14.3)	0.0
Proceeds from sale of equity investment	0.0	0.0	15.6
Proceeds related to business dispositions	3.3	0.0	1.2
Other investing activities, net	(7.7)	(4.3)	3.1
Net cash provided by (used in) investing activities	(77.6)	(443.8)	(50.2)
Cash flows from financing activities:
Net (repayments of) proceeds from debt	(17.9)	(36.1)	10.1
Debt issuance costs	(4.2)	0.0	(9.5)
Net inter-company proceeds (payments)	0.0	0.0	0.0
Redemption premium	0.0	0.0	(33.2)
Dividends paid to ordinary shareholders	(100.6)	(79.4)	(60.9)
Dividends paid	0.0	0.0	0.0
Proceeds from shares issued under incentive plans	6.5	3.2	7.2
Repurchase of ordinary shares	(226.0)	(67.3)	(60.0)
Other financing activities, net	0.0	(3.8)	(4.6)
Net cash provided by (used in) financing activities	(342.2)	(183.4)	(150.9)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(0.3)	(6.2)	7.7
Net increase (decrease) in cash, cash equivalents, and restricted cash	68.1	(175.6)	153.8
Cash, cash equivalents and restricted cash – beginning of period	290.6	466.2	312.4
Cash, cash equivalents and restricted cash – end of period	358.7	290.6	466.2
Allegion plc
Net cash provided by (used in) operating activities	(22.3)	209.3	581.3
Cash flows from investing activities:
Capital expenditures	0.0	0.0	0.0
Acquisition of and equity investments in businesses, net of cash acquired	0.0	0.0	0.0
Proceeds from sale of property, plant and equipment			0.0
Purchase of investments		0.0
Proceeds from sale of equity investment			0.0
Proceeds related to business dispositions	0.0		0.0
Other investing activities, net	0.0	0.0
Net cash provided by (used in) investing activities	0.0	0.0	0.0
Cash flows from financing activities:
Net (repayments of) proceeds from debt	(17.5)	(35.0)	(488.5)
Debt issuance costs	(4.2)		(4.0)
Net inter-company proceeds (payments)	365.2	(27.3)	49.7
Redemption premium			(24.6)
Dividends paid to ordinary shareholders	(100.6)	(79.4)	(60.9)
Dividends paid	0.0	0.0	0.0
Proceeds from shares issued under incentive plans	6.5	3.2	7.2
Repurchase of ordinary shares	(226.0)	(67.3)	(60.0)
Other financing activities, net	0.0	0.0	0.0
Net cash provided by (used in) financing activities	23.4	(205.8)	(581.1)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0.0	0.0	0.0
Net increase (decrease) in cash, cash equivalents, and restricted cash	1.1	3.5	0.2
Cash, cash equivalents and restricted cash – beginning of period	4.2	0.7	0.5
Cash, cash equivalents and restricted cash – end of period	5.3	4.2	0.7
Allegion US Holding
Net cash provided by (used in) operating activities	(54.7)	(59.5)	63.3
Cash flows from investing activities:
Capital expenditures	0.0	0.0	0.0
Acquisition of and equity investments in businesses, net of cash acquired	0.0	(248.5)	0.0
Proceeds from sale of property, plant and equipment			0.0
Purchase of investments		0.0
Proceeds from sale of equity investment			0.0
Proceeds related to business dispositions	0.0		0.0
Other investing activities, net	(7.5)	(1.0)
Net cash provided by (used in) investing activities	(7.5)	(249.5)	0.0
Cash flows from financing activities:
Net (repayments of) proceeds from debt	0.0	0.0	500.0
Debt issuance costs	0.0		(5.5)
Net inter-company proceeds (payments)	62.5	309.7	(546.3)
Redemption premium			(8.6)
Dividends paid to ordinary shareholders	0.0	0.0	0.0
Dividends paid	0.0	0.0	0.0
Proceeds from shares issued under incentive plans	0.0	0.0	0.0
Repurchase of ordinary shares	0.0	0.0	0.0
Other financing activities, net	0.0	0.0	(2.8)
Net cash provided by (used in) financing activities	62.5	309.7	(63.2)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0.0	0.0	0.0
Net increase (decrease) in cash, cash equivalents, and restricted cash	0.3	0.7	0.1
Cash, cash equivalents and restricted cash – beginning of period	1.0	0.3	0.2
Cash, cash equivalents and restricted cash – end of period	1.3	1.0	0.3
Other Subsidiaries
Net cash provided by (used in) operating activities	643.5	631.7	565.0
Cash flows from investing activities:
Capital expenditures	(65.6)	(49.1)	(49.3)
Acquisition of and equity investments in businesses, net of cash acquired	(7.6)	(127.6)	(20.8)
Proceeds from sale of property, plant and equipment			3.1
Purchase of investments		(14.3)
Proceeds from sale of equity investment			15.6
Proceeds related to business dispositions	3.3		1.2
Other investing activities, net	(7.7)	(4.3)
Net cash provided by (used in) investing activities	(77.6)	(195.3)	(50.2)
Cash flows from financing activities:
Net (repayments of) proceeds from debt	(0.4)	(1.1)	(1.4)
Debt issuance costs	0.0		0.0
Net inter-company proceeds (payments)	(427.7)	(282.4)	496.6
Redemption premium			0.0
Dividends paid to ordinary shareholders	0.0	0.0	0.0
Dividends paid	(78.3)	(323.7)	(862.4)
Proceeds from shares issued under incentive plans	0.0	0.0	0.0
Repurchase of ordinary shares	0.0	0.0	0.0
Other financing activities, net	7.5	(2.8)	(1.8)
Net cash provided by (used in) financing activities	(498.9)	(610.0)	(369.0)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(0.3)	(6.2)	7.7
Net increase (decrease) in cash, cash equivalents, and restricted cash	66.7	(179.8)	153.5
Cash, cash equivalents and restricted cash – beginning of period	285.4	465.2	311.7
Cash, cash equivalents and restricted cash – end of period	352.1	285.4	465.2
Consolidation Adjustments
Net cash provided by (used in) operating activities	(78.3)	(323.7)	(862.4)
Cash flows from investing activities:
Capital expenditures	0.0	0.0	0.0
Acquisition of and equity investments in businesses, net of cash acquired	0.0	0.0	0.0
Proceeds from sale of property, plant and equipment			0.0
Purchase of investments		0.0
Proceeds from sale of equity investment			0.0
Proceeds related to business dispositions	0.0		0.0
Other investing activities, net	7.5	1.0
Net cash provided by (used in) investing activities	7.5	1.0	0.0
Cash flows from financing activities:
Net (repayments of) proceeds from debt	0.0	0.0	0.0
Debt issuance costs	0.0		0.0
Net inter-company proceeds (payments)	0.0	0.0	0.0
Redemption premium
Dividends paid to ordinary shareholders	0.0	0.0	0.0
Dividends paid	78.3	323.7	862.4
Proceeds from shares issued under incentive plans	0.0	0.0	0.0
Repurchase of ordinary shares	0.0	0.0	0.0
Other financing activities, net	(7.5)	(1.0)	0.0
Net cash provided by (used in) financing activities	70.8	322.7	862.4
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0.0	0.0	0.0
Net increase (decrease) in cash, cash equivalents, and restricted cash	0.0	0.0	0.0
Cash, cash equivalents and restricted cash – beginning of period	0.0	0.0	0.0
Cash, cash equivalents and restricted cash – end of period	$ 0.0	$ 0.0	$ 0.0