Share-based Payment Expense - Summary of Assumptions of Fair Value Options (Detail)	1 Months Ended
May 31, 2019 EUR (€) yr € / shares	Apr. 30, 2019 EUR (€) yr € / shares	Apr. 30, 2018 EUR (€) yr € / shares	Mar. 31, 2017 EUR (€) yr € / shares
2010 Savings-Related Share Option Exercisable Within Six Months After Third Anniversary of Contract [member]
Disclosure Of Share Based Compensation Expense [line items]
Weighted average exercise price (€) \| € / shares	€ 24.24	€ 23.30	€ 23.39	€ 27.86
Risk free interest rate (%)	(0.58%)	(0.56%)	(0.44%)	(0.72%)
Expected dividend payments over the expected life (€) \| €	€ 2.34	€ 2.34	€ 2.21	€ 2.07
Expected volatility (%)	20.00%	19.60%	20.00%	20.90%
Expected life in years \| yr	3	3	3	3
2010 Savings Related Share Option Exercisable Within Six Months After Fifth Anniversary of Contract [member]
Disclosure Of Share Based Compensation Expense [line items]
Weighted average exercise price (€) \| € / shares	€ 24.24	€ 23.30	€ 23.39	€ 27.86
Risk free interest rate (%)	(0.41%)	(0.40%)	(0.06%)	(0.45%)
Expected dividend payments over the expected life (€) \| €	€ 4.06	€ 4.06	€ 3.83	€ 3.55
Expected volatility (%)	21.30%	21.10%	20.50%	20.60%
Expected life in years \| yr	5	5	5	5

Disclosure of share-based compensation expense.

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- Definition

The expected volatility of the share price used to calculate the fair value of the share options granted. Expected volatility is a measure of the amount by which a price is expected to fluctuate during a period. The measure of volatility used in option pricing models is the annualised standard deviation of the continuously compounded rates of return on the share over a period of time.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 2
-IssueDate 2019-01-01
-Paragraph 47
-Subparagraph a
-Clause i
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2019-en-r&anchor=para_47_a_i&doctype=Standard
-URIDate 2019-03-27

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- Definition

The option life of share options granted.

+ References

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- Definition

The implied yield currently available on zero-coupon government issues of the country in whose currency the exercise price for share options granted is expressed, with a remaining term equal to the expected term of the option being valued (based on the option's remaining contractual life and taking into account the effects of expected early exercise). [Refer: Government [member]]

+ References

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- Definition

The amount of an expected dividend used to calculate the fair value of share options granted.

+ References

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- Definition

The weighted average exercise price of share options granted in a share-based payment arrangement. [Refer: Weighted average [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 2
-IssueDate 2019-01-01
-Paragraph 45
-Subparagraph b
-Clause ii
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2019-en-r&anchor=para_45_b_ii&doctype=Standard
-URIDate 2019-03-27

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