Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
Operating revenue	$ 214,321	$ 204,710	$ 199,370
Operating expenses:
Costs of services provided	47,388	40,471	38,133
Product development	26,860	26,798	24,825
Sales and marketing	13,840	15,848	16,687
General and administrative (see Note 3)	36,880	36,480	33,562
Amortization and depreciation	9,681	10,107	9,155
Total operating expenses	134,649	129,704	122,362
Operating income	79,672	75,006	77,008
Interest income	379	518	441
Interest expense	(3,034)	(1,226)	(1,541)
Non-operating income - put options	296	342	190
Non-operating expense - securities litigation	(690)	(4,226)	0
Foreign exchange gain (loss)	829	(262)	1,931
Income before income taxes	77,452	70,152	78,029
Income tax provision	(13,894)	(10,878)	(7,460)
Net income	$ 63,558	$ 59,274	$ 70,569
Basic earnings per common share (in dollars per share)	$ 1.68	$ 1.58	$ 1.91
Diluted earnings per common share (in dollars per share)	$ 1.67	$ 1.53	$ 1.80
Basic weighted average shares outstanding (in shares)	37,809	37,588	36,948
Diluted weighted average shares outstanding (in shares)	38,040	38,642	39,100