BORROWINGS (Narrative) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013
Debt Disclosure [Abstract]
Total borrowings and other debt obligations	$ 37,383,063,000sov_BorrowingsAndOtherDebtObligations	$ 12,376,624,000sov_BorrowingsAndOtherDebtObligations
Borrowings repurchase	$ 600,000us-gaap_DebtInstrumentRepurchaseAmount		$ 5,400,000us-gaap_DebtInstrumentRepurchaseAmount

Fair value amount of debt instrument that was repurchased.

No definition available.

Name:	us-gaap_DebtInstrumentRepurchaseAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant