Goodwill & Other Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Goodwill	$ 186,980	$ 191,541	$ 160,252
Accumulated impairment losses	(15,417)	(15,417)	(15,417)
Acquisitions		35,646
Foreign currency translation	1,793	(4,357)
Purchase accounting adjustments	1,327
Divestitures	(7,681)
Total	171,563	176,124	144,835
Professional and Technical Services [Member]
Goodwill [Roll Forward]
Goodwill	59,917	58,573	45,438
Accumulated impairment losses	(6,367)	(6,367)	(6,367)
Acquisitions		14,033
Foreign currency translation	17	(898)
Purchase accounting adjustments	1,327
Divestitures	0
Total	53,550	52,206	39,071
Sandy Training and Marketing [Member]
Goodwill [Roll Forward]
Goodwill	127,063	132,968	114,814
Accumulated impairment losses	(9,050)	(9,050)	(9,050)
Acquisitions		21,613
Foreign currency translation	1,776	(3,459)
Purchase accounting adjustments	0
Divestitures	(7,681)
Total	$ 118,013	$ 123,918	$ 105,764