Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Revenue		$ 667,524	$ 642,410	$ 527,676
Expenses:
Cost of revenue	[1]	167,824	167,814	144,826
Sales and marketing	[1]	62,938	62,411	45,534
Research and development	[1]	33,503	33,686	28,638
General and administrative	[1]	216,624	200,762	205,038
Depreciation and amortization		114,925	108,250	96,725
Restructuring expense		0	0	9,500
Total operating expenses		595,814	572,923	530,261
Income (Loss) from operations		71,710	69,487	(2,585)
Other income and (expenses):
Interest income		479	2,242	2,181
Interest expense		(56,177)	(65,831)	(50,898)
Other expense, net		(551)	(20)	(2,255)
Income (Loss) before taxes		15,461	5,878	(53,557)
Benefit from income taxes		(7,118)	(1,897)	(14,393)
Net income (loss)		22,579	7,775	(39,164)
Net income (loss) attributable to common stockholders, basic and diluted		$ 21,906	$ 7,538	$ (39,164)
Net income (loss) per share attributable to common stockholders, basic and diluted:
Basic net income (loss) per share (in dollars per share)		$ 0.15	$ 0.05	$ (0.27)
Diluted net income (loss) per share (in dollars per share)		$ 0.15	$ 0.05	$ (0.27)
Weighted average shares of common stock outstanding:
Basic (in shares)		149,609	148,304	145,389
Diluted (in shares)		149,784	148,633	145,389

[1] (1) Includes stock-based compensation expense as follows:Cost of revenue$650 $348 $237 Sales and marketing2,841 1,675 735 Research and development1,293 1,707 1,937 General and administrative25,748 16,500 13,253 Total stock-based compensation expense$30,532 $20,230 $16,162