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 (loss)	(2,942)				(2,942)		114	(2,828)
Issuance (cancellation) of common stock in connection with exercise of Focus LLC common unit exchange rights (in shares)		254,441	(254,441)
Issuance of common stock in connection with exercise of Focus LLC incentive unit exchange rights	5,437	$ 2		5,435				5,437
Issuance of common stock in connection with exercise of Focus LLC incentive unit exchange rights (in shares)		149,271
Issuance (cancellation) of common stock in connection with exercise of Focus LLC common unit exchange rights	9,267	$ 3	$ (3)	9,267				9,267
Forfeiture of unvested Class A common stock	(30)			(30)				(30)
Forfeiture of unvested Class A common stock		(909)
Exercise of stock options	214			214				214
Exercise of stock options (in shares)		6,477
Change in non-controlling interest allocation	(28,347)			(28,347)			14,126	(14,221)
Non-cash equity compensation expense	705			705				705
Currency translation adjustment - net of tax	230					230	124	354
Adjustment of deferred tax assets, net of amounts payable under tax receivable agreements and changes from Focus LLC interest transactions	858			858				858
Ending balance at Mar. 31, 2019	455,054	$ 467	$ 225	459,488	(3,532)	(1,594)	357,222	812,276
Ending Balance (in shares) at Mar. 31, 2019		46,675,183	22,568,831
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 (loss)	20,396				20,396		13,623	34,019
Issuance (cancellation) of common stock in connection with exercise of Focus LLC common unit exchange rights	6,036	$ 3	$ (3)	6,036				6,036
Issuance (cancellation) of common stock in connection with exercise of Focus LLC common unit exchange rights (in shares)		316,370	(316,370)
Issuance of common stock in connection with exercise of Focus LLC incentive unit exchange rights	1,272	$ 1		1,271				1,272
Issuance of common stock in connection with exercise of Focus LLC incentive unit exchange rights (in shares)		66,631
Exercise of stock options	77			77				77
Exercise of stock options (in shares)		2,713
Change in non-controlling interest allocation	14,087			14,087			(21,530)	(7,443)
Non-cash equity compensation expense	1,017			1,017				1,017
Currency translation adjustment - net of tax	(5,524)					(5,524)	(3,041)	(8,565)
Unrealized loss on interest rate swap designated as a cash flow hedge	(1,923)					(1,923)	(1,021)	(2,944)
Adjustment of deferred tax assets, net of amounts payable under tax receivable agreements and changes from Focus LLC interest transactions	(393)			(393)				(393)
Ending balance at Mar. 31, 2020	$ 519,165	$ 478	$ 218	$ 520,281	$ 6,934	$ (8,746)	$ 307,881	$ 827,046
Ending Balance (in shares) at Mar. 31, 2020		47,807,029	21,759,379