CONDENSED CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income [Member]	Noncontrolling Interest [Member]	Preferred Class A [Member] Series A Convertible Preferred Stock [Member]	Common Class A [Member] Common Stock [Member]	Common Class B [Member]	Common Class B [Member] Common Stock [Member]
Beginning balance at Dec. 31, 2018	$ 229,321	$ 2,003,518	$ (1,578,076)	$ (216,650)	$ 301	$ 0	$ 20,228		$ 0
Beginning balance (in shares) at Dec. 31, 2018						1
Beginning balance (in shares) at Dec. 31, 2018							252,853,554		0
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Stock-based compensation	2,127	2,127
Shares issuance, stock-based compensation (in shares)							705,744
Share issuance, stock-based compensation	0	(57)					$ 57
Withholding tax on net share settlement of stock-based compensation	(373)	(373)
Net income / (loss)	55,829		55,717		112
Unrealized gain / (loss) on derivative instruments	(4,551)			(4,551)
Currency translation adjustment	1,159			1,113	46
Ending balance at Jun. 30, 2019	283,512	2,005,215	(1,522,359)	(220,088)	459	$ 0	$ 20,285		$ 0
Ending balance (in shares) at Jun. 30, 2019						1
Ending balance (in shares) at Jun. 30, 2019							253,559,298		0
Beginning balance at Mar. 31, 2019	222,602	2,004,188	(1,566,318)	(235,961)	431	$ 0	$ 20,262		$ 0
Beginning balance (in shares) at Mar. 31, 2019						1
Beginning balance (in shares) at Mar. 31, 2019							253,279,975		0
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Stock-based compensation	1,124	1,124
Shares issuance, stock-based compensation (in shares)							279,323
Share issuance, stock-based compensation	0	(23)					$ 23
Withholding tax on net share settlement of stock-based compensation	(74)	(74)
Net income / (loss)	44,078		43,959		119
Unrealized gain / (loss) on derivative instruments	(1,220)			(1,220)
Currency translation adjustment	17,002			17,093	(91)
Ending balance at Jun. 30, 2019	283,512	2,005,215	(1,522,359)	(220,088)	459	$ 0	$ 20,285		$ 0
Ending balance (in shares) at Jun. 30, 2019						1
Ending balance (in shares) at Jun. 30, 2019							253,559,298		0
Beginning balance at Dec. 31, 2019	342,218	2,007,275	(1,458,942)	(226,916)	513	$ 0	$ 20,288		$ 0
Beginning balance (in shares) at Dec. 31, 2019						1
Beginning balance (in shares) at Dec. 31, 2019							253,607,026	0	0
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Stock-based compensation	1,672	1,672
Shares issuance, stock-based compensation (in shares)							941,154
Share issuance, stock-based compensation	0	(76)					$ 76
Withholding tax on net share settlement of stock-based compensation	(11)	(11)
Net income / (loss)	40,072		40,220		(148)
Unrealized gain / (loss) on derivative instruments	342			342
Currency translation adjustment	(35,466)			(35,487)	21
Ending balance at Jun. 30, 2020	348,827	2,008,860	(1,418,722)	(262,061)	386	$ 0	$ 20,364		$ 0
Ending balance (in shares) at Jun. 30, 2020						1
Ending balance (in shares) at Jun. 30, 2020							254,548,180	0	0
Beginning balance at Mar. 31, 2020	291,290	2,008,151	(1,449,901)	(287,919)	616	$ 0	$ 20,343		$ 0
Beginning balance (in shares) at Mar. 31, 2020						1
Beginning balance (in shares) at Mar. 31, 2020							254,298,255		0
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Stock-based compensation	733	733
Shares issuance, stock-based compensation (in shares)							249,925
Share issuance, stock-based compensation	0	(21)					$ 21
Withholding tax on net share settlement of stock-based compensation	(3)	(3)
Net income / (loss)	31,102		31,179		(77)
Unrealized gain / (loss) on derivative instruments	122			122
Currency translation adjustment	25,583			25,736	(153)
Ending balance at Jun. 30, 2020	$ 348,827	$ 2,008,860	$ (1,418,722)	$ (262,061)	$ 386	$ 0	$ 20,364		$ 0
Ending balance (in shares) at Jun. 30, 2020						1
Ending balance (in shares) at Jun. 30, 2020							254,548,180	0	0