Segment Information (Depreciation and Amortization) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Depreciation and amortization	$ 182,336	$ 178,486	$ 173,312
North America Mailing | Small & Medium Business Solutions
Segment Reporting Information [Line Items]
Depreciation and amortization	64,803	60,066	58,141
International Mailing | Small & Medium Business Solutions
Segment Reporting Information [Line Items]
Depreciation and amortization	18,562	19,431	23,262
Production Mail | Enterprise Business Solutions
Segment Reporting Information [Line Items]
Depreciation and amortization	2,686	4,421	4,075
Presort Services | Enterprise Business Solutions
Segment Reporting Information [Line Items]
Depreciation and amortization	26,541	27,929	27,305
Software Solutions | Digital Commerce Solutions
Segment Reporting Information [Line Items]
Depreciation and amortization	8,978	14,621	18,151
Global Ecommerce | Digital Commerce Solutions
Segment Reporting Information [Line Items]
Depreciation and amortization	36,662	30,607	21,025
Operating Segments
Segment Reporting Information [Line Items]
Depreciation and amortization	158,232	157,075	154,016
Operating Segments | Small & Medium Business Solutions
Segment Reporting Information [Line Items]
Depreciation and amortization	83,365	79,497	81,403
Operating Segments | Enterprise Business Solutions
Segment Reporting Information [Line Items]
Depreciation and amortization	29,227	32,350	31,380
Operating Segments | Digital Commerce Solutions
Segment Reporting Information [Line Items]
Depreciation and amortization	45,640	45,228	39,176
Operating Segments | Other
Segment Reporting Information [Line Items]
Depreciation and amortization	0	0	2,057
Unallocated amount
Segment Reporting Information [Line Items]
Depreciation and amortization	$ 24,104	$ 21,411	$ 19,296