Annual report pursuant to Section 13 and 15(d)

ACQUISITIONS - Narrative (Details)

v3.8.0.1
ACQUISITIONS - Narrative (Details)
$ in Thousands, € in Millions
Mar. 01, 2017
USD ($)
Mar. 01, 2017
EUR (€)
Feb. 28, 2017
USD ($)
Jan. 13, 2017
USD ($)
Jan. 13, 2017
EUR (€)
Jan. 03, 2017
USD ($)
Jan. 03, 2017
EUR (€)
Nov. 30, 2016
USD ($)
Nov. 30, 2016
EUR (€)
Feb. 01, 2016
USD ($)
Aug. 19, 2015
USD ($)
Sep. 30, 2017
USD ($)
Sep. 30, 2016
USD ($)
Sep. 30, 2015
USD ($)
Business Acquisition [Line Items]                            
Goodwill                       $ 897,794 $ 851,489 $ 855,728
GJ Creative Limited                            
Business Acquisition [Line Items]                            
Purchase price of acquisition $ 37,596 € 30.5                        
RAF Technology, Inc.                            
Business Acquisition [Line Items]                            
Purchase price of acquisition     $ 8,717                      
VCG (Holdings) Limited                            
Business Acquisition [Line Items]                            
Purchase price of acquisition       $ 10,695 € 8.8                  
Ungricht                            
Business Acquisition [Line Items]                            
Purchase price of acquisition           $ 25,185 € 24.0              
Guidance Automation Limited                            
Business Acquisition [Line Items]                            
Purchase price of acquisition               $ 9,974 € 8.0          
Digital Design, Inc.                            
Business Acquisition [Line Items]                            
Purchase price of acquisition                   $ 8,773        
Aurora                            
Business Acquisition [Line Items]                            
Purchase price of acquisition                     $ 210,026      
Goodwill                     73,927      
Intangible assets acquired                     76,340      
Intangible assets not subject to amortization                     30,540      
Property plant and equipment acquired                     26,268      
Other net assets acquired                     33,491      
Goodwill expected to be deductible for tax purposes                     $ 44,000