Short-Term Borrowings - Additional Information (Detail) $ in Billions	Dec. 31, 2016 USD ($)
Short-term Debt [Line Items]
Deposits with the Federal Reserve	$ 1.8
Federal Reserve Bank of Cleveland [Member]
Short-term Debt [Line Items]
Unused Secured borrowing capacity	27.4
Federal Home Loan Bank of Cincinnati [Member]
Short-term Debt [Line Items]
Unused Secured borrowing capacity	$ 6.4

Amount of unused borrowing capacity under the long-term financing arrangement that is available to the entity as of the balance sheet date.

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 210.5-02.22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant