Revision of Previously Issued Financial Statements (Consolidated Statements of Income) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Net service revenues	$ 193,987	$ 168,993	$ 568,779	$ 456,415
Gross profit	56,301	45,176	167,133	121,696
General and administrative expenses	40,733	35,085	125,470	94,109
Total operating expenses	43,778	37,841	134,342	101,474
Operating income from continuing operations	12,523	7,335	32,791	20,222
Income from continuing operations before income taxes	11,930	7,255	31,058	19,154
Income tax expense	2,811	1,769	6,374	4,080
Net income from continuing operations	9,119	5,486	24,684	15,074
Net income	$ 9,119	$ 4,912	$ 24,684	$ 14,500
Basic income per share	$ 0.58	$ 0.36	$ 1.59	$ 1.10
Diluted income per share	$ 0.57	$ 0.35	$ 1.55	$ 1.06
As Previously Reported [Member]
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Net service revenues		$ 169,803		$ 458,749
Gross profit		45,986		124,030
General and administrative expenses		35,950		95,429
Total operating expenses		38,706		102,794
Operating income from continuing operations		7,280		21,236
Income from continuing operations before income taxes		7,200		20,168
Income tax expense		1,759		4,347
Net income from continuing operations		5,441		15,821
Net income		$ 4,867		$ 15,247
Basic income per share		$ 0.36		$ 1.15
Diluted income per share		$ 0.34		$ 1.12
Revision [Member]
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Net service revenues		$ (810)		$ (2,334)
Gross profit		(810)		(2,334)
General and administrative expenses		(865)		(1,320)
Total operating expenses		(865)		(1,320)
Operating income from continuing operations		55		(1,014)
Income from continuing operations before income taxes		55		(1,014)
Income tax expense		10		(267)
Net income from continuing operations		45		(747)
Net income		$ 45		$ (747)
Basic income per share				$ (0.05)
Diluted income per share		$ 0.01		$ (0.06)