Provisions for employee benefits (Details 1) € in Millions	12 Months Ended
Dec. 31, 2018 EUR (€)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 EUR (€)
Statement [Line Items]
Present value of benefit liabilities at beginning of year	€ 31		€ 3
Interest cost/income			(15)
Present value of benefit liabilities at end of year (a)	136		31
Change in asset ceiling	5
Asset ceiling at end of year (c)	5
Net liability recognized at end of year (a+b+c)	1,117		1,022
Italian defined benefit plans [Member]
Statement [Line Items]
Net liability recognized at end of year (a+b+c)	275		284
Foreign defined benefit plan [Member]
Statement [Line Items]
Current cost	27		24
Interest cost/income	(14)		(9)
Past service cost and (gains) losses settlements	2		(1)
Asset ceiling at end of year (c)	5
Net liability recognized at end of year (a+b+c)	385		409
FISDE and other foreign medical plans [Member]
Statement [Line Items]
Current cost	2		2
Interest cost/income	(2)		(2)
Past service cost and (gains) losses settlements	1		2
Net liability recognized at end of year (a+b+c)	148		135
Defined benefit plan [Member]
Statement [Line Items]
Current cost	29		26
Interest cost/income	(20)		(14)
Past service cost and (gains) losses settlements	3		1
Asset ceiling at end of year (c)	5
Net liability recognized at end of year (a+b+c)	808		828
Other benefit plans [Member]
Statement [Line Items]
Current cost	42		54
Interest cost/income	(1)		(1)
Past service cost and (gains) losses settlements	115		28
Net liability recognized at end of year (a+b+c)	309		194
Present value of defined benefit obligation [member]
Statement [Line Items]
Present value of benefit liabilities at beginning of year	1,610		1,487
Current cost	71		80
Interest cost/income	38		35
Remeasurements:	19		50
- actuarial (gains) losses due to changes in demographic assumptions			(14)
- actuarial (gains) losses due to changes in financial assumptions	(1)		69
- experience (gains) losses	20		(5)
Past service cost and (gains) losses settlements	118		29
Plan contributions:			1
- employee contributions	1		1
Benefits paid	(133)		(89)
Reclassification to asset held for sale	(8)		(14)
Changes in the scope of consolidation	(92)		(20)
Currency translation differences and other changes	34		51
Present value of benefit liabilities at end of year (a)	1,657		1,610
Present value of defined benefit obligation [member] \| Italian defined benefit plans [Member]
Statement [Line Items]
Present value of benefit liabilities at beginning of year	284		298
Interest cost/income	4		3
Remeasurements:	1		(6)
- actuarial (gains) losses due to changes in financial assumptions			(5)
- experience (gains) losses	1		(1)
Benefits paid	(15)		(10)
Changes in the scope of consolidation			(1)
Currency translation differences and other changes	1
Present value of benefit liabilities at end of year (a)	275		284
Present value of defined benefit obligation [member] \| Foreign defined benefit plan [Member]
Statement [Line Items]
Present value of benefit liabilities at beginning of year	997		895
Current cost	27		24
Interest cost/income	31		29
Remeasurements:	(25)		54
- actuarial (gains) losses due to changes in demographic assumptions			(14)
- actuarial (gains) losses due to changes in financial assumptions	(31)		71
- experience (gains) losses	6		(3)
Past service cost and (gains) losses settlements	2		(1)
Plan contributions:			1
- employee contributions	1		1
Benefits paid	(35)		(37)
Reclassification to asset held for sale	(8)		(12)
Changes in the scope of consolidation	(90)		(15)
Currency translation differences and other changes	26		59
Present value of benefit liabilities at end of year (a)	925		997
Present value of defined benefit obligation [member] \| FISDE and other foreign medical plans [Member]
Statement [Line Items]
Present value of benefit liabilities at beginning of year	135		136
Current cost	2		2
Interest cost/income	2		2
Remeasurements:	13		(1)
- actuarial (gains) losses due to changes in financial assumptions	1
- experience (gains) losses	12		(1)
Past service cost and (gains) losses settlements	1		2
Benefits paid	(9)		(6)
Changes in the scope of consolidation			(1)
Currency translation differences and other changes	4		1
Present value of benefit liabilities at end of year (a)	148		135
Present value of defined benefit obligation [member] \| Defined benefit plan [Member]
Statement [Line Items]
Present value of benefit liabilities at beginning of year	1,416		1,329
Current cost	29		26
Interest cost/income	37		34
Remeasurements:	(11)		47
- actuarial (gains) losses due to changes in demographic assumptions			(14)
- actuarial (gains) losses due to changes in financial assumptions	(30)		66
- experience (gains) losses	19		(5)
Past service cost and (gains) losses settlements	3		1
Plan contributions:			1
- employee contributions	1		1
Benefits paid	(59)		(53)
Reclassification to asset held for sale	(8)		(12)
Changes in the scope of consolidation	(90)		(17)
Currency translation differences and other changes	31		60
Present value of benefit liabilities at end of year (a)	1,348		1,416
Present value of defined benefit obligation [member] \| Other benefit plans [Member]
Statement [Line Items]
Present value of benefit liabilities at beginning of year	194		158
Current cost	42		54
Interest cost/income	1		1
Remeasurements:	30		3
- actuarial (gains) losses due to changes in financial assumptions	29		3
- experience (gains) losses	1
Past service cost and (gains) losses settlements	115		28
Benefits paid	(74)		(36)
Reclassification to asset held for sale			(2)
Changes in the scope of consolidation	(2)		(3)
Currency translation differences and other changes	3		(9)
Present value of benefit liabilities at end of year (a)	309		194
Plan assets [member]
Statement [Line Items]
Present value of benefit liabilities at beginning of year	588		619
Interest cost/income	17		20
Return on plan assets	(21)		12
Plan contributions:	25		24
- employee contributions	1		1
- employer contributions	24		23
Benefits paid	(26)		(25)
Changes in the scope of consolidation	(64)		(15)
Currency translation differences and other changes	26		(47)
Present value of benefit liabilities at end of year (a)	545		588
Change in asset ceiling \| $		$ 5
Plan assets [member] \| Italian defined benefit plans [Member]
Statement [Line Items]
Changes in the scope of consolidation	(64)
Plan assets [member] \| Foreign defined benefit plan [Member]
Statement [Line Items]
Present value of benefit liabilities at beginning of year	588		619
Interest cost/income	17		20
Return on plan assets	(21)		12
Plan contributions:	25		24
- employee contributions	1		1
- employer contributions	24		23
Benefits paid	(26)		(25)
Changes in the scope of consolidation			(15)
Currency translation differences and other changes	26		(47)
Present value of benefit liabilities at end of year (a)	545		588
Change in asset ceiling \| $		5
Plan assets [member] \| Defined benefit plan [Member]
Statement [Line Items]
Present value of benefit liabilities at beginning of year	588		619
Interest cost/income	17		20
Return on plan assets	(21)		12
Plan contributions:	25		24
- employee contributions	1		1
- employer contributions	24		23
Benefits paid	(26)		(25)
Changes in the scope of consolidation	(64)		(15)
Currency translation differences and other changes	26		(47)
Present value of benefit liabilities at end of year (a)	€ 545		€ 588
Change in asset ceiling \| $		$ 5

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Ifrs Statement

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Represent the Increase decrease through changes in foreign exchange rates and other changes net defined benefit liability asset.

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No definition available.

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The decrease (increase) in a net defined benefit liability (asset) resulting from actuarial gains (losses) arising from changes in demographic assumptions that result in remeasurements of the net defined benefit liability (asset). Demographic assumptions deal with matters such as: (a) mortality; (b) rates of employee turnover, disability and early retirement; (c) the proportion of plan members with dependants who will be eligible for benefits; (d) the proportion of plan members who will select each form of payment option available under the plan terms; and (e) claim rates under medical plans. [Refer: Net defined benefit liability (asset)]

+ References

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The decrease (increase) in a net defined benefit liability (asset) resulting from actuarial gains (losses) arising from changes in financial assumptions that result in remeasurements of the net defined benefit liability (asset). Financial assumptions deal with items such as: (a) the discount rate; (b) benefit levels, excluding any cost of the benefits to be met by employees, and future salary; (c) in the case of medical benefits, future medical costs, including claim handling costs (ie the costs that will be incurred in processing and resolving claims, including legal and adjuster's fees); and (d) taxes payable by the plan on contributions relating to service before the reporting date or on benefits resulting from that service. [Refer: Net defined benefit liability (asset)]

+ References

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The decrease (increase) in a net defined benefit liability (asset) resulting from actuarial gains (losses) arising from experience adjustments that result in remeasurements of the net defined benefit liability (asset). Experience adjustments deal with the effects of differences between the previous actuarial assumptions and what has actually occurred. [Refer: Net defined benefit liability (asset)]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition

The decrease (increase) in net defined benefit liability (asset) resulting from contributions to a defined benefit plan by the employer. [Refer: Net defined benefit liability (asset); Defined benefit plans [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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The decrease (increase) in the net defined benefit liability (asset) resulting from contributions to a defined benefit plan by plan participants. [Refer: Net defined benefit liability (asset); Defined benefit plans [member]]

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The decrease (increase) in the net defined benefit liability (asset) resulting from contributions to a defined benefit plan. [Refer: Net defined benefit liability (asset); Defined benefit plans [member]]

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The increase (decrease) in the net defined benefit liability (asset) resulting from employee service in the current period. [Refer: Net defined benefit liability (asset)]

+ References

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The decrease (increase) in the net defined benefit liability (asset) resulting from the gain (loss) on changes in the effect of limiting a net defined benefit asset to the asset ceiling, excluding amounts included in interest income or expense. [Refer: Interest income; Net defined benefit liability (asset); Interest expense (income), net defined benefit liability (asset)]

+ References

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The decrease (increase) in a net defined benefit liability (asset) resulting from the remeasurement of that net defined benefit liability (asset). [Refer: Net defined benefit liability (asset)]

+ References

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The increase (decrease) in the net defined benefit liability (asset) resulting from business combinations and disposals. [Refer: Business combinations [member]; Net defined benefit liability (asset)]

+ References

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The increase (decrease) in the net defined benefit liability (asset) resulting from the passage of time. [Refer: Interest expense; Net defined benefit liability (asset)]

+ References

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The amount of deficit or surplus in a defined benefit plan, adjusted for any effect of limiting a net defined benefit asset to the asset ceiling. [Refer: Defined benefit plans [member]]

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The increase (decrease) in the net defined benefit liability (asset) resulting from past service cost and gains (losses) arising from settlements. [Refer: Gains (losses) arising from settlements, net defined benefit liability (asset); Net defined benefit liability (asset)]

+ References

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The decrease (increase) in the net defined benefit liability (asset) resulting from payments from the plan in respect of settlements. [Refer: Gains (losses) arising from settlements, net defined benefit liability (asset); Net defined benefit liability (asset); Defined benefit plans [member]]

+ References

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The decrease (increase) in the net defined benefit liability (asset) resulting from the return on plan assets, excluding amounts included in interest income or expense. The return on plans assets is interest, dividends and other revenue derived from the plan assets, together with realised and unrealised gains or losses on the plan assets, less any costs of managing plan assets and less any tax payable by the plan itself, other than tax included in the actuarial assumptions used to measure the present value of the defined benefit obligation. [Refer: Plan assets [member]; Net defined benefit liability (asset); Actuarial assumptions [member]; Interest expense (income), net defined benefit liability (asset)]

+ References

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The fair value of any plan assets, less the present value of the defined benefit obligation. [Refer: Plan assets [member]]

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