Segment Information (Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Assets	$ 4,272,185	$ 4,741,355	$ 4,958,871
Cash and cash equivalents	601,053	669,981
Short-term investments	22,166	11,172
Long-term investments	250,240	259,977
Identifiable long-lived assets	717,169	744,288	672,364
United States
Segment Reporting Information [Line Items]
Identifiable long-lived assets	703,484	730,347	658,070
Outside United States
Segment Reporting Information [Line Items]
Identifiable long-lived assets	13,685	13,941	14,294
Operating Segments
Segment Reporting Information [Line Items]
Assets	3,152,719	3,529,662	3,525,187
Operating Segments | Global Ecommerce
Segment Reporting Information [Line Items]
Assets	597,073	996,297	1,032,434
Operating Segments | Presort Services
Segment Reporting Information [Line Items]
Assets	500,757	510,345	479,392
Operating Segments | SendTech Solutions
Segment Reporting Information [Line Items]
Assets	2,054,889	2,023,020	2,013,361
Reconciling Items
Segment Reporting Information [Line Items]
Cash and cash equivalents	601,053	669,981	732,480
Short-term investments	22,166	11,172	14,440
Long-term investments	250,240	259,977	333,052
Other corporate assets	$ 246,007	$ 270,563	$ 353,712