Segment Information (Revenues) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Revenue	$ 983,712	$ 875,449	$ 899,203	$ 915,197	$ 1,028,417	$ 891,898	$ 837,492	$ 796,268	$ 3,673,561	$ 3,554,075	$ 3,205,125
United States
Segment Reporting Information [Line Items]
Revenue									3,114,905	3,112,285	2,745,928
Outside United States
Segment Reporting Information [Line Items]
Revenue									558,656	441,790	459,197
Digital Commerce Solutions | Global Ecommerce
Segment Reporting Information [Line Items]
Total from contracts with customers									1,702,580	1,618,897	1,151,510
Digital Commerce Solutions | Presort Services
Segment Reporting Information [Line Items]
Total from contracts with customers									573,480	521,212	529,588
SendTech Solutions
Segment Reporting Information [Line Items]
Total from contracts with customers									$ 1,397,501	$ 1,413,966	$ 1,524,027