CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
CONDENSED CONSOLIDATED STATEMENTS OF INCOME
Revenue		$ 105,013	$ 105,459	$ 331,495	$ 316,710
Expenses:
Cost of revenue	[1]	35,433	38,394	120,570	103,847
Sales and marketing	[1]	7,037	3,946	19,712	8,173
Research and development	[1]	7,404	6,283	21,047	17,198
General and administrative	[1]	37,209	32,437	105,222	82,022
Depreciation and amortization		8,904	5,526	25,794	15,253
Total operating expenses		95,987	86,586	292,345	226,493
Income from operations		9,026	18,873	39,150	90,217
Other income and (expenses):
Realized gains (losses) on short-term investments		9	(329)	4	(329)
Gain on disposal of equipment				534
Interest income		1,450	1,184	4,424	1,807
Interest expense		(1,302)	(1,110)	(3,806)	(3,318)
Income before taxes		9,183	18,618	40,306	88,377
Provision for income taxes		1,376	8,498	13,883	38,362
Net income		7,807	10,120	26,423	50,015
Net income attributable to common stockholders, basic and diluted		$ 7,771	$ 10,115	$ 26,308	$ 50,003
Net income per share attributable to common stockholders, basic and diluted:
Basic net income per share (in dollars per share)		$ 0.05	$ 0.07	$ 0.17	$ 0.35
Diluted net income per share (in dollars per share)		$ 0.05	$ 0.07	$ 0.17	$ 0.34
Weighted average shares of common stock outstanding:
Basic (in shares)		150,732	148,871	151,240	144,000
Diluted (in shares)		151,562	151,835	152,122	147,409

[1] Includes stock-based compensation expense as follows: Three months ended September 30, 2016: Cost of revenue 94; Sales and marketing 140; Research and development 186; General and administrative 1,704; Total stock-based compensation expense 2,124. Three months ended September 30, 2015: Cost of revenue 28; Sales and marketing 66; Research and development 2,928; General and administrative 1,619; Total stock-based compensation expense 2,005. Nine months ended September 30, 2016: Cost of revenue 334; Sales and marketing 446; Research and development 927; General and administrative 4,645; Total stock-based compensation expense 6.352. Nine months ended September 30, 2015: Cost of revenue 85; Sales and marketing 122; Research and development 952; General and administrative 4,540; Total stock-based compensation expense 5,699.