CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
CONDENSED CONSOLIDATED STATEMENTS OF INCOME
Revenue		$ 117,618	$ 100,957	$ 211,251	$ 185,631
Expenses:
Cost of revenue	[1]	33,602	28,899	65,453	57,486
Sales and marketing	[1]	2,377	1,612	4,227	2,945
Research and development	[1]	5,504	5,144	10,915	11,192
General and administrative	[1]	25,327	21,341	49,585	41,275
Depreciation and amortization		4,812	5,114	9,727	9,969
Total operating expenses		71,622	62,110	139,907	122,867
Income from operations		45,996	38,847	71,344	62,764
Other income and (expenses):
Interest income		615	1	623	3
Interest expense		(1,105)	(49)	(2,208)	(62)
Income before taxes		45,506	38,799	69,759	62,705
Provision for income taxes		19,370	15,169	29,864	24,518
Net income		26,136	23,630	39,895	38,187
Net income attributable to common stockholders, basic and diluted		$ 26,131	$ 23,630	$ 39,891	$ 38,187
Basic net income per share		$ 0.18	$ 0.18	$ 0.28	$ 0.28
Diluted net income per share		$ 0.17	$ 0.17	$ 0.27	$ 0.28
Weighted average shares of common stock outstanding:
Basic		147,648	134,523	141,524	134,585
Diluted		151,299	136,814	145,149	135,635

[1] Includes stock-based compensation expense as follows: Three months ended June 30, 2015: Cost of revenue 29; Sales and marketing 41; Research and development 298; General and administrative 1,554; Total stock-based compensation expense 1,922. Three months ended June 30, 2015: General and administrative 436; Total stock-based compensation expense 436. Six months ended June 30, 2015: Cost of revenue 57; Sales and marketing 56; Research and development 660; General and administrative 2,921; Total stock-based compensation expense 3,694. Six months ended June 30, 2014: General and administrative 822; Total stock-based compensation expense 822.