v3.10.0.1
Intangible Assets Including Goodwill - Summary of Intangible Assets Including Goodwill (Detail) - EUR (€)
€ in Millions
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]    
Beginning balance, intangible assets € 27  
Ending balance, intangible assets 28 € 27
Beginning balance 162  
Ending balance 174 162
Goodwill    
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]    
Beginning balance 135  
Ending balance 146 135
Cost    
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]    
Beginning balance, intangible assets 35 20
Additions 8 12
Acquisition, business combination (Note 5) 3 17
Amortization charge 0  
Write off of fully amortized intangibles   (13)
Exchange differences 1 (1)
Ending balance, intangible assets 47 35
Beginning balance 170 93
Additions 8 12
Acquisition, business combination (Note 5) 11 88
Write off of fully amortized intangibles   (13)
Exchange differences 4 (10)
Ending balance 193 170
Cost | Goodwill    
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]    
Beginning balance 135 73
Additions 0 0
Acquisition, business combination (Note 5) 8 71
Exchange differences 3 (9)
Ending balance 146 135
Accumulated Depreciation    
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]    
Beginning balance, intangible assets (8) (13)
Amortization charge (11) (8)
Write off of fully amortized intangibles   13
Ending balance, intangible assets (19) (8)
Beginning balance (8) (13)
Write off of fully amortized intangibles   13
Ending balance (19) (8)
Internal development costs and patents    
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]    
Beginning balance, intangible assets 12  
Ending balance, intangible assets 14 12
Internal development costs and patents | Cost    
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]    
Beginning balance, intangible assets 18 8
Additions 8 12
Acquisition, business combination (Note 5) 0 0
Amortization charge 0  
Write off of fully amortized intangibles   (2)
Exchange differences 0 0
Ending balance, intangible assets 26 18
Internal development costs and patents | Accumulated Depreciation    
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]    
Beginning balance, intangible assets (6) (3)
Amortization charge (6) (5)
Write off of fully amortized intangibles   2
Ending balance, intangible assets (12) (6)
Acquired intangible assets    
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]    
Beginning balance, intangible assets 15  
Ending balance, intangible assets 14 15
Acquired intangible assets | Cost    
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]    
Beginning balance, intangible assets 17 12
Additions 0 0
Acquisition, business combination (Note 5) 3 17
Amortization charge 0  
Write off of fully amortized intangibles   (11)
Exchange differences 1 (1)
Ending balance, intangible assets 21 17
Acquired intangible assets | Accumulated Depreciation    
Disclosure Of Reconciliation Of Changes In Intangible Assets And Goodwill [Line Items]    
Beginning balance, intangible assets (2) (10)
Amortization charge (5) (3)
Write off of fully amortized intangibles   11
Ending balance, intangible assets € (7) € (2)