Segment Information (EBIT) (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended								12 Months Ended
	Mar. 31, 2020	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciling items:
Goodwill impairment										$ (198,169)	$ 0	$ 0
Loss on extinguishment of debt	$ 37,000									36,987	6,623	7,964
Gain on sale of equity investment										21,969	0	0
(Provision) benefit for income taxes		$ 813	$ (554)	$ (17,016)	$ 10,030	$ (344)	$ 24,895	$ (3,724)	$ (7,820)	(6,727)	13,007	(6,416)
(Loss) income from continuing operations										(191,659)	40,149	181,705
Income from discontinued operations, net of tax		2,467	616	(3,032)	10,064	168,659	(8,470)	(5,613)	(116)	10,115	154,460	60,106
Net (loss) income		$ 18,879	$ 11,389	$ (3,329)	(208,483)	$ 176,696	$ (3,125)	$ 23,697	$ (2,659)	(181,544)	194,609	241,811
Commerce Services
Reconciling items:
Goodwill impairment										(198,169)
Commerce Services | Global Ecommerce
Segment Reporting Information [Line Items]
EBIT										(82,894)	(70,146)	(32,379)
Reconciling items:
Goodwill impairment					$ (198,000)					(198,169)
Commerce Services | Presort Services
Segment Reporting Information [Line Items]
EBIT										55,799	70,693	73,768
Reconciling items:
Goodwill impairment										0
SendTech Solutions
Reconciling items:
Goodwill impairment										0
Operating Segments
Segment Reporting Information [Line Items]
EBIT										413,990	490,869	600,348
Operating Segments | Commerce Services
Segment Reporting Information [Line Items]
EBIT										(27,095)	547	41,389
Operating Segments | SendTech Solutions
Segment Reporting Information [Line Items]
EBIT										441,085	490,322	558,959
Reconciling Items
Reconciling items:
Interest, net										(153,915)	(155,558)	(159,757)
Unallocated corporate expenses										(200,406)	(211,529)	(185,919)
Restructuring charges and asset impairments										(20,712)	(69,606)	(25,899)
Goodwill impairment										(198,169)	0	0
Loss on extinguishment of debt										(36,987)	(6,623)	(7,964)
Gain on sale of equity investment										11,908	0	0
Pension settlement										0	0	(31,329)
Loss on sale of businesses										0	(17,683)	0
Transaction costs										(641)	$ (2,728)	$ (1,359)
Insurance proceeds										$ 17,000