Business segment information (disaggregated revenue information) (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2017
Disaggregated revenue information
Number of reportable business segments	3
Total revenue from external customers	$ 491,914	$ 487,766
Product revenue	363,407	372,174
Service revenue	128,507	115,592
United States [Member]
Disaggregated revenue information
Total revenue from external customers	459,724
Foreign, primarily Canada and Australia [Member]
Disaggregated revenue information
Total revenue from external customers	32,190
Small Business Services [Member]
Disaggregated revenue information
Total revenue from external customers	316,313	308,123
Small Business Services [Member] | United States [Member]
Disaggregated revenue information
Total revenue from external customers	289,598
Small Business Services [Member] | Foreign, primarily Canada and Australia [Member]
Disaggregated revenue information
Total revenue from external customers	26,715	18,979
Financial Services [Member]
Disaggregated revenue information
Total revenue from external customers	140,641	140,794
Financial Services [Member] | United States [Member]
Disaggregated revenue information
Total revenue from external customers	135,166
Financial Services [Member] | Foreign, primarily Canada and Australia [Member]
Disaggregated revenue information
Total revenue from external customers	5,475
Direct Checks [Member]
Disaggregated revenue information
Total revenue from external customers	34,960	38,849
Direct Checks [Member] | United States [Member]
Disaggregated revenue information
Total revenue from external customers	34,960
Direct Checks [Member] | Foreign, primarily Canada and Australia [Member]
Disaggregated revenue information
Total revenue from external customers	0
Checks [Member]
Disaggregated revenue information
Total revenue from external customers	210,338	222,173
Checks [Member] | Small Business Services [Member]
Disaggregated revenue information
Total revenue from external customers	122,932	124,137
Checks [Member] | Financial Services [Member]
Disaggregated revenue information
Total revenue from external customers	58,051	65,375
Checks [Member] | Direct Checks [Member]
Disaggregated revenue information
Total revenue from external customers	29,355	32,661
Small business marketing solutions [Member]
Disaggregated revenue information
Total revenue from external customers	66,762	59,509
Small business marketing solutions [Member] | Small Business Services [Member]
Disaggregated revenue information
Total revenue from external customers	66,762	59,509
Small business marketing solutions [Member] | Financial Services [Member]
Disaggregated revenue information
Total revenue from external customers	0	0
Small business marketing solutions [Member] | Direct Checks [Member]
Disaggregated revenue information
Total revenue from external customers	0	0
Web services [Member]
Disaggregated revenue information
Total revenue from external customers	37,376	30,244
Web services [Member] | Small Business Services [Member]
Disaggregated revenue information
Total revenue from external customers	37,376	30,244
Web services [Member] | Financial Services [Member]
Disaggregated revenue information
Total revenue from external customers	0	0
Web services [Member] | Direct Checks [Member]
Disaggregated revenue information
Total revenue from external customers	0	0
Data-driven marketing solutions [Member]
Disaggregated revenue information
Total revenue from external customers	37,140	32,074
Data-driven marketing solutions [Member] | Small Business Services [Member]
Disaggregated revenue information
Total revenue from external customers	0	0
Data-driven marketing solutions [Member] | Financial Services [Member]
Disaggregated revenue information
Total revenue from external customers	37,140	32,074
Data-driven marketing solutions [Member] | Direct Checks [Member]
Disaggregated revenue information
Total revenue from external customers	0	0
Treasury management solutions [Member]
Disaggregated revenue information
Total revenue from external customers	29,200	22,774
Treasury management solutions [Member] | Small Business Services [Member]
Disaggregated revenue information
Total revenue from external customers	0	0
Treasury management solutions [Member] | Financial Services [Member]
Disaggregated revenue information
Total revenue from external customers	29,200	22,774
Treasury management solutions [Member] | Direct Checks [Member]
Disaggregated revenue information
Total revenue from external customers	0	0
Fraud, security, risk management and operational services [Member]
Disaggregated revenue information
Total revenue from external customers	22,680	27,500
Fraud, security, risk management and operational services [Member] | Small Business Services [Member]
Disaggregated revenue information
Total revenue from external customers	6,516	6,633
Fraud, security, risk management and operational services [Member] | Financial Services [Member]
Disaggregated revenue information
Total revenue from external customers	12,307	16,611
Fraud, security, risk management and operational services [Member] | Direct Checks [Member]
Disaggregated revenue information
Total revenue from external customers	3,857	4,256
Total MOS [Member]
Disaggregated revenue information
Total revenue from external customers	193,158	172,101
Product revenue	64,651
Service revenue	128,507
Total MOS [Member] | Small Business Services [Member]
Disaggregated revenue information
Total revenue from external customers	110,654	96,386
Total MOS [Member] | Financial Services [Member]
Disaggregated revenue information
Total revenue from external customers	78,647	71,459
Total MOS [Member] | Direct Checks [Member]
Disaggregated revenue information
Total revenue from external customers	3,857	4,256
Forms, accessories and other products [Member]
Disaggregated revenue information
Total revenue from external customers	88,418	93,492
Forms, accessories and other products [Member] | Small Business Services [Member]
Disaggregated revenue information
Total revenue from external customers	82,727	87,600
Forms, accessories and other products [Member] | Financial Services [Member]
Disaggregated revenue information
Total revenue from external customers	3,943	3,960
Forms, accessories and other products [Member] | Direct Checks [Member]
Disaggregated revenue information
Total revenue from external customers	$ 1,748	$ 1,932
Product concentration risk [Member] | Checks [Member] | Small Business Services [Member]
Disaggregated revenue information
Concentration risk, percentage			39.00%
Product concentration risk [Member] | Checks [Member] | Financial Services [Member]
Disaggregated revenue information
Concentration risk, percentage			43.00%
Product concentration risk [Member] | Checks [Member] | Direct Checks [Member]
Disaggregated revenue information
Concentration risk, percentage			84.00%
Product concentration risk [Member] | Total MOS [Member] | Small Business Services [Member]
Disaggregated revenue information
Concentration risk, percentage			34.00%
Product concentration risk [Member] | Total MOS [Member] | Financial Services [Member]
Disaggregated revenue information
Concentration risk, percentage			55.00%
Product concentration risk [Member] | Total MOS [Member] | Direct Checks [Member]
Disaggregated revenue information
Concentration risk, percentage			11.00%