Segment Reporting (Revenue and Adjusted EBITDA for each Reportable Segment) (Details) - USD ($) $ in Thousands		12 Months Ended
		Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Net revenue		$ 3,480,815	$ 3,090,421	$ 196,792
Adjusted EBITDA		1,071,051	934,165
Reconciliation of income (loss) before tax provision (benefit) to Adjusted EBITDA
Income (loss) before income tax provision (benefit)		(106,001)	(147,397)	(1,090,851)
Amortization of capitalized software developed for sale		3,509	1,326
Depreciation and amortization		681,808	591,048	30,838
Interest expense		234,244	245,241	16,652
Equity compensation		95,730	59,016
Acquisition accounting adjustments		(11,839)	109,743
Acquisition and divestiture-related costs		41,120	19,709
Integration and related costs		26,803	40,675
Strategic initiatives, duplicative and transition costs		46,041	21,841
Severance costs		10,178	13,184
Accretion and changes in estimate, net		25,276	11,644	15,823
Impairment of long-lived assets and other		4,958	18,190
Loss on extinguishment of debt		3,885	8,924
Gain on sale of businesses			(59,143)
Contingent consideration			(3,000)
Other non-routine, net		15,339	3,164
Adjusted EBITDA		1,071,051	934,165
Postage and Eliminations [Member]
Segment Reporting Information [Line Items]
Net revenue	[1]	82,727	96,533
Purchase Accounting Adjustment [Member]
Segment Reporting Information [Line Items]
Net revenue	[2]	(7,740)	(128,230)
Software and Analytics [Member]
Segment Reporting Information [Line Items]
Net revenue		1,612,931	1,534,926
Adjusted EBITDA		561,994	526,129
Reconciliation of income (loss) before tax provision (benefit) to Adjusted EBITDA
Adjusted EBITDA		561,994	526,129
Network Solutions [Member]
Segment Reporting Information [Line Items]
Net revenue		868,425	717,843
Adjusted EBITDA		446,378	377,005
Reconciliation of income (loss) before tax provision (benefit) to Adjusted EBITDA
Adjusted EBITDA		446,378	377,005
Technology-Enabled Services [Member]
Segment Reporting Information [Line Items]
Net revenue		924,472	869,349
Adjusted EBITDA		62,679	31,031
Reconciliation of income (loss) before tax provision (benefit) to Adjusted EBITDA
Adjusted EBITDA		62,679	31,031
Postage [Member]
Segment Reporting Information [Line Items]
Net revenue		$ 219,612	$ 196,532	$ 12,631

[1] Revenue for the Postage and Eliminations segment includes postage revenue of $219,612 and $196,532 for the years ended March 31, 2022 and 2021, respectively.

[2] Amount reflects the impact to deferred revenue resulting from the Merger which reduced revenue recognized during the period.