Business segment information (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016 USD ($) customers	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($) customers	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) customers	Dec. 31, 2015 USD ($) customers	Dec. 31, 2014 USD ($) customers
Business segment information [Line Items]
Number of reportable business segments									3
Total revenue from external customers:	$ 480,202	$ 458,920	$ 450,642	$ 459,298	$ 463,510	$ 439,816	$ 435,874	$ 433,617	$ 1,849,062	$ 1,772,817	$ 1,674,082
Operating income									368,727	354,331	332,633
Depreciation and amortization expense:									91,583	76,700	65,842
Asset impairment charges									0	0	6,468
Total assets	$ 2,184,338				$ 1,842,153				2,184,338	1,842,153	1,683,682
Capital asset purchases:									$ 46,614	$ 43,261	$ 41,119
Customer concentration risk [Member]
Business segment information [Line Items]
Number of customers | customers	0				0				0	0	0
Customer concentration risk [Member] | Total revenue benchmark [Member]
Business segment information [Line Items]
Concentration risk, percentage									10.00%	10.00%	10.00%
Checks [Member]
Business segment information [Line Items]
Total revenue from external customers:									$ 865,285	$ 873,298	$ 870,910
Small Business Services [Member] | Checks [Member] | Product concentration risk [Member]
Business segment information [Line Items]
Concentration risk, percentage									39.10%
Financial Services [Member] | Checks [Member] | Customer concentration risk [Member]
Business segment information [Line Items]
Concentration risk, percentage									53.80%
Direct Checks [Member] | Checks [Member] | Customer concentration risk [Member]
Business segment information [Line Items]
Concentration risk, percentage									84.10%
Reportable business segments [Member] | Small Business Services [Member]
Business segment information [Line Items]
Total revenue from external customers:									$ 1,195,743	1,151,916	1,106,505
Operating income									208,789	203,933	187,226
Depreciation and amortization expense:									52,195	45,513	44,418
Asset impairment charges									0	0	6,468
Total assets	$ 1,086,500				$ 995,445				1,086,500	995,445	949,521
Capital asset purchases:									0	0	0
Reportable business segments [Member] | Financial Services [Member]
Business segment information [Line Items]
Total revenue from external customers:									499,976	455,390	391,129
Operating income									106,820	91,539	87,908
Depreciation and amortization expense:									35,850	26,807	14,675
Asset impairment charges									0	0	0
Total assets	631,353				435,632				631,353	435,632	274,086
Capital asset purchases:									0	0	0
Reportable business segments [Member] | Direct Checks [Member]
Business segment information [Line Items]
Total revenue from external customers:									153,343	165,511	176,448
Operating income									53,118	58,859	57,499
Depreciation and amortization expense:									3,538	4,380	6,749
Asset impairment charges									0	0	0
Total assets	161,039				161,987				161,039	161,987	164,171
Capital asset purchases:									0	0	0
Corporate [Member]
Business segment information [Line Items]
Depreciation and amortization expense related to corporate assets which was allocated to segments									32,785	32,505	34,801
Total revenue from external customers:									0	0	0
Operating income									0	0	0
Depreciation and amortization expense:									0	0	0
Asset impairment charges									0	0	0
Total assets	$ 305,446				$ 249,089				305,446	249,089	295,904
Capital asset purchases:									$ 46,614	$ 43,261	$ 41,119