Quarterly report pursuant to Section 13 or 15(d)

Goodwill and Other Intangible Assets - Other Intangible Assets (Details)

v3.21.1
Goodwill and Other Intangible Assets - Other Intangible Assets (Details) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2021
Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]    
Remaining Weighted Average Amortization Period in Years 6 years 8 months 12 days  
Intangible Assets $ 952,108 $ 950,229
Accumulated Amortization (539,986) (517,574)
Intangible Assets, Net 412,122 432,655
Indefinite-lived Intangible Assets [Line Items]    
Intangible Assets 955,108 953,229
Intangible Assets, Net 415,122 435,655
Engineering license    
Indefinite-lived Intangible Assets [Line Items]    
Intangible Assets $ 3,000 3,000
Customer relationships    
Finite-Lived Intangible Assets [Line Items]    
Remaining Weighted Average Amortization Period in Years 5 years 4 months 24 days  
Intangible Assets $ 618,035 616,875
Accumulated Amortization (295,700) (277,647)
Intangible Assets, Net $ 322,335 339,228
Backlog    
Finite-Lived Intangible Assets [Line Items]    
Remaining Weighted Average Amortization Period in Years 1 year 1 month 6 days  
Intangible Assets $ 150,096 149,769
Accumulated Amortization (146,852) (145,476)
Intangible Assets, Net $ 3,244 4,293
Trade names    
Finite-Lived Intangible Assets [Line Items]    
Remaining Weighted Average Amortization Period in Years 13 years 7 months 6 days  
Intangible Assets $ 101,711 101,533
Accumulated Amortization (33,960) (32,471)
Intangible Assets, Net $ 67,751 69,062
Non-compete agreements    
Finite-Lived Intangible Assets [Line Items]    
Remaining Weighted Average Amortization Period in Years 3 years  
Intangible Assets $ 47,537 47,333
Accumulated Amortization (38,105) (36,973)
Intangible Assets, Net $ 9,432 10,360
Patented rights and developed technology    
Finite-Lived Intangible Assets [Line Items]    
Remaining Weighted Average Amortization Period in Years 3 years 3 months 18 days  
Intangible Assets $ 22,496 22,486
Accumulated Amortization (21,940) (21,894)
Intangible Assets, Net $ 556 592
Curriculum    
Finite-Lived Intangible Assets [Line Items]    
Remaining Weighted Average Amortization Period in Years 7 years 1 month 6 days  
Intangible Assets $ 12,233 12,233
Accumulated Amortization (3,429) (3,113)
Intangible Assets, Net $ 8,804 $ 9,120