Segment Information (Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Assets	$ 4,958,871	$ 5,224,363	$ 5,469,958
Cash and cash equivalents	732,480	921,450
Short-term investments	14,440	18,974
Long-term investments	333,052	364,212
Identifiable long-lived assets	672,364	631,631	618,154
United States
Segment Reporting Information [Line Items]
Identifiable long-lived assets	658,070	613,990	596,694
Outside United States
Segment Reporting Information [Line Items]
Identifiable long-lived assets	14,294	17,641	21,460
Global Ecommerce
Segment Reporting Information [Line Items]
Assets	35,000
Digital Commerce Solutions | Global Ecommerce
Segment Reporting Information [Line Items]
Assets	1,032,434	994,554	1,102,313
Digital Commerce Solutions | Presort Services
Segment Reporting Information [Line Items]
Assets	479,392	523,690	524,817
Operating Segments
Segment Reporting Information [Line Items]
Assets	3,525,187	3,589,272	3,783,936
Operating Segments | SendTech Solutions
Segment Reporting Information [Line Items]
Assets	2,013,361	2,071,028	2,156,806
Reconciling Items
Segment Reporting Information [Line Items]
Cash and cash equivalents	732,480	921,450	924,442
Short-term investments	14,440	18,974	115,879
Assets of discontinued operations	0	0	17,229
Long-term investments	333,052	364,212	238,882
Other corporate assets	$ 353,712	$ 330,455	$ 389,590