Interim Financial Data by Segment - Schedule of Financial Data Segment Reporting Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2026	Mar. 31, 2025
Segment Reporting Information [Line Items]
Revenues	$ 1,953.6	$ 1,811.7	$ 5,256.9	$ 4,823.7
Depreciation and amortization	35.6	32.6	101.6	97.6
Amortization of acquired intangibles	52.8	48.9	155.2	146.6
Amortization of other assets	41.6	42.1	126.2	128.0
Other direct expenses	1,483.0	1,377.1	3,949.9	3,864.2
Other segment items	0.0	0.0	0.0	0.0
Earnings before income taxes	340.6	310.9	923.9	587.2
Corporate and Other
Segment Reporting Information [Line Items]
Revenues	0.0	0.0	0.0	0.0
Depreciation and amortization	12.2	7.9	29.8	24.6
Amortization of acquired intangibles	0.0	0.0	0.0	0.0
Amortization of other assets	5.5	4.4	16.7	13.1
Other direct expenses	158.0	153.0	220.3	433.1
Other segment items	(121.4)	(112.9)	(387.8)	(326.9)
Earnings before income taxes	(54.3)	(52.4)	121.0	(143.8)
Investor Communication Solutions
Segment Reporting Information [Line Items]
Revenues	1,465.3	1,347.5	3,828.5	3,512.3
Investor Communication Solutions | Operating Segments
Segment Reporting Information [Line Items]
Revenues	1,465.3	1,347.5	3,828.5	3,512.3
Depreciation and amortization	12.1	11.4	35.5	33.6
Amortization of acquired intangibles	11.1	10.6	31.5	33.1
Amortization of other assets	8.6	9.5	28.8	29.5
Other direct expenses	1,035.9	948.3	2,878.0	2,635.0
Other segment items	88.0	74.8	282.1	217.6
Earnings before income taxes	309.5	292.9	572.7	563.5
Global Technology And Operations
Segment Reporting Information [Line Items]
Revenues	3.5		14.7
Global Technology And Operations | Operating Segments
Segment Reporting Information [Line Items]
Revenues	488.3	464.1	1,428.4	1,311.4
Depreciation and amortization	11.4	13.3	36.2	39.4
Amortization of acquired intangibles	41.7	38.3	123.8	113.5
Amortization of other assets	27.4	28.2	80.7	85.4
Other direct expenses	289.0	275.7	851.6	796.2
Other segment items	33.4	38.2	105.7	109.4
Earnings before income taxes	85.4	70.4	230.3	167.5
Total Reportable Segments | Operating Segments
Segment Reporting Information [Line Items]
Revenues	1,953.6	1,811.7	5,256.9	4,823.7
Depreciation and amortization	23.5	24.7	71.8	73.1
Amortization of acquired intangibles	52.8	48.9	155.2	146.6
Amortization of other assets	36.1	37.7	109.5	114.9
Other direct expenses	1,324.9	1,224.0	3,729.6	3,431.1
Other segment items	121.4	112.9	387.8	326.9
Earnings before income taxes	$ 394.9	$ 363.3	$ 803.0	$ 731.0