Unaudited Condensed Consolidated Statements of Changes in Members' Deficit/Shareholders' Equity - USD ($) $ in Thousands	Total Shareholders' Equity	Common Stock Class A common stock	Common Stock Class B common stock	Additional Paid-In Capital	Retained Earnings (Deficit)	Accumulated Other Comprehensive Loss	Non-controlling Interest	Total
Beginning balance at Dec. 31, 2018	$ 469,662	$ 462	$ 228	$ 471,386	$ (590)	$ (1,824)	$ 342,858	$ 812,520
Beginning balance (in shares) at Dec. 31, 2018		46,265,903	22,823,272
Increase (Decrease) in shareholders' equity
Net income	(2,146)				(2,146)		2,420	274
Issuance (cancellation) of common stock in connection with exercise of Focus LLC common unit exchange rights (in shares)		514,826	(514,826)
Issuance of common stock in connection with exercise of Focus LLC incentive unit exchange rights	9,975	$ 3		9,972				9,975
Issuance of common stock in connection with exercise of Focus LLC incentive unit exchange rights (in shares)		312,871
Issuance (cancellation) of common stock in connection with exercise of Focus LLC common unit exchange rights	16,572	$ 6	$ (5)	16,571				16,572
Forfeiture of unvested Class A common stock	(30)			(30)				(30)
Forfeiture of unvested Class A common stock (in shares)		(909)
Exercise of stock options	796			796				796
Exercise of stock options (in shares)		24,126
Change in non-controlling interest allocation	(11,032)			(11,032)			(14,790)	(25,822)
Non-cash equity compensation expense	1,653			1,653				1,653
Currency translation adjustment - net of tax	(176)					(176)	(157)	(333)
Adjustment of deferred tax assets, net of amounts payable under tax receivable agreements and changes from Focus LLC interest transactions	250			250				250
Ending balance at Jun. 30, 2019	485,524	$ 471	$ 223	489,566	(2,736)	(2,000)	330,331	815,855
Ending Balance (in shares) at Jun. 30, 2019		47,116,817	22,308,446
Beginning balance at Mar. 31, 2019	455,054	$ 467	$ 225	459,488	(3,532)	(1,594)	357,222	812,276
Beginning balance (in shares) at Mar. 31, 2019		46,675,183	22,568,831
Increase (Decrease) in shareholders' equity
Net income	796				796		2,306	3,102
Issuance (cancellation) of common stock in connection with exercise of Focus LLC common unit exchange rights	7,305	$ 3	$ (2)	7,304				7,305
Issuance (cancellation) of common stock in connection with exercise of Focus LLC common unit exchange rights (in shares)		260,385	(260,385)
Issuance of common stock in connection with exercise of Focus LLC incentive unit exchange rights	4,538	$ 1		4,537				4,538
Issuance of common stock in connection with exercise of Focus LLC incentive unit exchange rights (in shares)		163,600
Exercise of stock options	582			582				582
Exercise of stock options (in shares)		17,649
Change in non-controlling interest allocation	17,315			17,315			(28,916)	(11,601)
Non-cash equity compensation expense	948			948				948
Currency translation adjustment - net of tax	(406)					(406)	(281)	(687)
Adjustment of deferred tax assets, net of amounts payable under tax receivable agreements and changes from Focus LLC interest transactions	(608)			(608)				(608)
Ending balance at Jun. 30, 2019	485,524	$ 471	$ 223	489,566	(2,736)	(2,000)	330,331	815,855
Ending Balance (in shares) at Jun. 30, 2019		47,116,817	22,308,446
Beginning balance at Dec. 31, 2019	484,120	$ 474	$ 221	498,186	(13,462)	(1,299)	319,850	803,970
Beginning balance (in shares) at Dec. 31, 2019		47,421,315	22,075,749
Increase (Decrease) in shareholders' equity
Net income	22,805				22,805		14,542	37,347
Issuance (cancellation) of common stock in connection with exercise of Focus LLC common unit exchange rights	13,366	$ 6	$ (6)	13,366				13,366
Issuance (cancellation) of common stock in connection with exercise of Focus LLC common unit exchange rights (in shares)		579,646	(579,646)
Issuance of common stock in connection with exercise of Focus LLC incentive unit exchange rights	1,803	$ 1		1,802				1,803
Issuance of common stock in connection with exercise of Focus LLC incentive unit exchange rights (in shares)		85,702
Forfeiture of unvested Class A common stock	(27)			(27)				(27)
Forfeiture of unvested Class A common stock (in shares)		(834)
Exercise of stock options	167			167				167
Exercise of stock options (in shares)		5,878
Change in non-controlling interest allocation	(12,128)			(12,128)			(4,017)	(16,145)
Non-cash equity compensation expense	2,190			2,190				2,190
Currency translation adjustment - net of tax	(1,810)					(1,810)	(977)	(2,787)
Unrealized loss on interest rate swap designated as a cash flow hedge	(5,407)					(5,407)	(2,920)	(8,327)
Adjustment of deferred tax assets, net of amounts payable under tax receivable agreements and changes from Focus LLC interest transactions	(347)			(347)				(347)
Ending balance at Jun. 30, 2020	504,732	$ 481	$ 215	503,209	9,343	(8,516)	326,478	831,210
Ending Balance (in shares) at Jun. 30, 2020		48,091,707	21,496,103
Beginning balance at Mar. 31, 2020	519,165	$ 478	$ 218	520,281	6,934	(8,746)	307,881	827,046
Beginning balance (in shares) at Mar. 31, 2020		47,807,029	21,759,379
Increase (Decrease) in shareholders' equity
Net income	2,409				2,409		919	3,328
Issuance (cancellation) of common stock in connection with exercise of Focus LLC common unit exchange rights	7,330	$ 3	$ (3)	7,330				7,330
Issuance (cancellation) of common stock in connection with exercise of Focus LLC common unit exchange rights (in shares)		263,276	(263,276)
Issuance of common stock in connection with exercise of Focus LLC incentive unit exchange rights	531			531				531
Issuance of common stock in connection with exercise of Focus LLC incentive unit exchange rights (in shares)		19,071
Forfeiture of unvested Class A common stock	(27)			(27)				(27)
Forfeiture of unvested Class A common stock (in shares)		(834)
Exercise of stock options	90			90				90
Exercise of stock options (in shares)		3,165
Change in non-controlling interest allocation	(26,215)			(26,215)			17,513	(8,702)
Non-cash equity compensation expense	1,173			1,173				1,173
Currency translation adjustment - net of tax	3,714					3,714	2,064	5,778
Unrealized loss on interest rate swap designated as a cash flow hedge	(3,484)					(3,484)	(1,899)	(5,383)
Adjustment of deferred tax assets, net of amounts payable under tax receivable agreements and changes from Focus LLC interest transactions	46			46				46
Ending balance at Jun. 30, 2020	$ 504,732	$ 481	$ 215	$ 503,209	$ 9,343	$ (8,516)	$ 326,478	$ 831,210
Ending Balance (in shares) at Jun. 30, 2020		48,091,707	21,496,103