Shareholders' equity (Details) (USD $) In Thousands, unless otherwise specified	1 Months Ended	6 Months Ended
	Apr. 30, 2013	Jun. 30, 2013	Jun. 30, 2012
Shares outstanding
Common shares issued related to Banker's Dashboard, LLC acquisition	193
Number of years after closing that shares were requried to be issued, minimum	2 years
Share repurchases
Common shares authorized for repurchase		10,000
Common shares that remain available for repurchase		3,442
Common shares repurchased (in shares)		(815)
Payments for common shares repurchased		$ 32,000	$ 11,999