Commercial Paper and Other Short-Term Borrowings - Additional Information (Details)	Dec. 31, 2015	Dec. 31, 2014
Federal funds purchased and securities sold under repurchase agreements
Commercial Paper and Short-Term Borrowings
Weighted average interest rate (as a percent)	0.30%	0.12%
Commercial paper
Commercial Paper and Short-Term Borrowings
Weighted average interest rate (as a percent)	0.23%	0.16%

Weighted average interest rate of short-term debt outstanding.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant