Business Combinations, Goodwill and Intangible Assets - Supplemental Pro Forma Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
SCIO
Business Acquisition [Line Items]
Revenues	$ 924,172	$ 834,158
Net income	$ 55,756	$ 45,827
Earnings per share:
Basic (in dollars per share)	$ 1.62	$ 1.35
Diluted (in dollars per share)	$ 1.59	$ 1.30
Health Integrated, Inc.
Business Acquisition [Line Items]
Revenues	$ 801,101	$ 729,938
Net income	$ 46,998	$ 58,232
Earnings per share:
Basic (in dollars per share)	$ 1.39	$ 1.73
Diluted (in dollars per share)	$ 1.34	$ 1.68