Significant accounting policies - Retained earnings impact of IFRS 16 adoption (Detail) - EUR (€) € in Millions	Dec. 31, 2019	Dec. 31, 2018
Significant accounting policies - Text Details (Detail) [Line Items]
Retained earnings		€ 8,266
Deferred tax assets	€ 1,865	1,828
After presentation change [Member]
Significant accounting policies - Text Details (Detail) [Line Items]
Retained earnings		8,233
Deferred tax assets		1,833
IFRS 16 [Member]
Significant accounting policies - Text Details (Detail) [Line Items]
Impact on equity		(38)
Deferred tax assets		€ 5

The amounts of income taxes recoverable in future periods in respect of: (a) deductible temporary differences; (b) the carryforward of unused tax losses; and (c) the carryforward of unused tax credits. [Refer: Temporary differences [member]; Unused tax credits [member]; Unused tax losses [member]]

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