Derivatives (assets and liabilities) and Short positions (Tables)

12 Months Ended

Dec. 31, 2017

Derivatives And Short Positions [Abstract]

Schedule by type of inherent risk of fair value of derivatives

	Millions of euros
	2017		2016		2015
	Debit	Credit	Debit	Credit	Debit	Credit
	balance	balance	balance	balance	balance	balance
Interest rate risk	38,030	37,582	47,884	48,124	51,576	49,095
Currency risk	16,320	18,014	21,087	23,500	21,924	23,444
Price risk	2,167	2,040	2,599	2,402	2,598	3,343
Other risks	726	256	473	343	626	532
	57,243	57,892	72,043	74,369	76,724	76,414

Schedule of short positions (liabilities)

	Millions of euros
	2017	2016	2015
Borrowed securities:
Debt instruments	2,447	2,250	3,098
Of which: Santander UK plc	1,557	1,319	1,857
Equity instruments	1,671	1,142	990
Of which: Santander UK plc	1,500	991	905
Short sales:
Debt instruments	16,861	19,613	13,274
Of which:
Banco Santander, S.A.	8,621	7,472	6,953
Banco Santander (México), S.A., Institución de Banca Múltiple, Grupo Financiero Santander México	46	1,872	1,290
Banco Santander (Brasil) S.A.	8,188	9,197	4,619
Equity instruments	—	—	—
	20,979	23,005	17,362