Summary of Significant Accounting Policies - Narrative (Details) client in Thousands, $ in Millions	3 Months Ended
	Jun. 30, 2019 USD ($) client country	Jun. 30, 2018
Accounting Policies [Abstract]
Number of clients served | client	6
Number of countries in which entity operates | country	70
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Change in depreciation expense | $	$ (49)
Discontinued Operations, Disposed of by Means Other than Sale, Spinoff | USPS Separation
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Share exchange ratio		0.5