CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Revenue		$ 166,453	$ 145,809	$ 468,921	$ 391,362
Expenses:
Cost of revenue	[1]	42,940	36,422	121,261	108,928
Sales and marketing	[1]	16,172	11,785	44,004	31,732
Research and development	[1]	9,060	7,580	25,159	21,546
General and administrative	[1]	49,306	47,203	148,623	156,773
Depreciation and amortization		26,903	26,571	81,370	69,857
Restructuring expense		0	0	0	9,464
Total operating expenses		144,381	129,561	420,417	398,300
Income (Loss) from operations		22,072	16,248	48,504	(6,938)
Other income and (expenses):
Interest income		619	325	1,893	1,874
Interest expense		(16,700)	(16,824)	(49,891)	(34,274)
Other expense, net		(7)	(210)	(18)	(1,841)
Income (Loss) before taxes		5,984	(461)	488	(41,179)
(Benefit from) Provision for income taxes		(858)	383	(2,569)	(13,035)
Net income (loss)		6,842	(844)	3,057	(28,144)
Net income (loss) attributable to common stockholders, basic and diluted		$ 6,621	$ (844)	$ 2,965	$ (28,144)
Net income (loss) per share attributable to common stockholders, basic and diluted:
Basic net (loss) income per share (in dollars per share)		$ 0.04	$ (0.01)	$ 0.02	$ (0.19)
Diluted net (loss) income per share (in dollars per share)		$ 0.04	$ (0.01)	$ 0.02	$ (0.19)
Weighted average shares of common stock outstanding:
Basic (in shares)		148,456	147,339	148,124	144,662
Diluted (in shares)		148,797	147,339	148,473	144,662

[1] (1) Includes stock-based compensation expense as follows:      
          Cost of revenue $ 116
  $ 101
  $ 271
  $ 154
  Sales and marketing 535
  308
  1,174
  376
  Research and development 475
  643
  1,224
  1,601
  General and administrative 4,659
  3,702
  11,137
  9,015
  Total stock-based compensation expense $ 5,785
  $ 4,754
  $ 13,806
  $ 11,146