CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
Revenues	$ 837,630	$ 711,764	$ 575,936
Cost of revenues	173,814	188,885	156,979
Gross margin	663,816	522,879	418,957
Operating expenses:
Selling and marketing	296,483	302,226	150,305
Software development	76,400	65,760	55,426
General and administrative	123,297	115,507	103,916
Customer base amortization	22,731	27,931	28,432
Total operating expenses	518,911	511,424	338,079
Income from operations	144,905	11,455	80,878
Interest and other income	1,773	537	516
Interest and other expense	(10,016)	(9,411)	(10,481)
Income before income taxes	136,662	2,581	70,913
Income tax expense, net	51,591	6,046	26,044
Net income (loss)	$ 85,071	$ (3,465)	$ 44,869
Net income (loss) per share — basic (in dollars per share)	$ 2.64	$ (0.11)	$ 1.48
Net income (loss) per share — diluted (in dollars per share)	$ 2.62	$ (0.11)	$ 1.46
Weighted average outstanding shares — basic (in shares)	32,167	31,950	30,215
Weighted average outstanding shares — diluted (in shares)	32,436	31,950	30,641