CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($)		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Revenues	[1]	$ 356,036,000	$ 388,645,000	$ 419,482,000
Cost of revenues	[1],[2],[3]	180,712,000	199,622,000	200,220,000
Selling and marketing	[2],[3]	70,220,000	89,145,000	108,395,000
Research and development	[2],[3]	38,706,000	61,802,000	76,979,000
General and administrative	[1],[2],[3]	55,783,000	66,419,000	84,535,000
Amortization of intangible assets		27,219,000	30,076,000	32,864,000
Impairment of right-of-use and long-lived assets		4,671,000	0	0
Impairment of goodwill		0	224,272,000	0
Impairment of intangible asset		0	17,308,000	0
Investigation and audit related		0	4,305,000	38,338,000
Restructuring	[3]	0	3,263,000	11,837,000
Settlement of litigation, net		0	2,900,000	5,250,000
Total expenses from operations		377,311,000	699,112,000	558,418,000
Loss from operations		(21,275,000)	(310,467,000)	(138,936,000)
Interest expense, net	[1]	(35,805,000)	(31,526,000)	(16,465,000)
Other income (expense), net		14,554,000	1,654,000	(1,464,000)
(Loss) gain from foreign currency transactions		(4,490,000)	336,000	1,303,000
Loss before income taxes		(47,016,000)	(340,003,000)	(155,562,000)
Income tax (provision) benefit		(902,000)	1,007,000	(3,706,000)
Net loss		$ (47,918,000)	$ (338,996,000)	$ (159,268,000)
Net loss per common share:
Basic and diluted (in dollars per share)		$ (0.67)	$ (5.33)	$ (2.76)
Weighted-average number of shares used in per share calculation - Common Stock:
Basic and diluted (in shares)		71,181,496	63,590,882	57,700,603
Comprehensive loss:
Net loss		$ (47,918,000)	$ (338,996,000)	$ (159,268,000)
Other comprehensive income (loss):
Foreign currency cumulative translation adjustment		5,303,000	(1,712,000)	(4,397,000)
Total comprehensive loss		$ (42,615,000)	$ (340,708,000)	$ (163,665,000)

[1] Transactions with related parties are included in the line items above as follows (refer to Footnote 13, Related Party Transactions, of the Notes to Consolidated Financial Statements for additional information): Years Ended December 31,202020192018Revenues$13,314 $17,464 $12,662 Cost of revenues10,094 10,490 11,239 General and administrative316 776 650 Interest expense, net(24,480)(23,494)(16,023)

[2] Excludes amortization of intangible assets, which is presented separately in the Consolidated Statements of Operations and Comprehensive Loss.

[3] Stock-based compensation expense is included in the line items above as follows: Years Ended December 31,202020192018Cost of revenues$1,288 $1,852 $6,349 Selling and marketing2,226 3,615 9,452 Research and development886 1,981 6,580 General and administrative5,673 9,247 14,770 Restructuring— (137)468 Total stock-based compensation expense$10,073 $16,558 $37,619