Short-Term Borrowings - Summary of Unused Lines of Credit (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Line of Credit Facility [Line Items]
Total unused lines of credit	$ 527,181	$ 413,032
FNBB [Member]
Line of Credit Facility [Line Items]
Total unused lines of credit	30,000	30,000
JPMorgan Chase [Member]
Line of Credit Facility [Line Items]
Total unused lines of credit	30,000	30,000
FHLB [Member]
Line of Credit Facility [Line Items]
Total unused lines of credit	432,181	338,032
PNC Bank [Member]
Line of Credit Facility [Line Items]
Total unused lines of credit	15,000	15,000
Comerica [Member]
Line of Credit Facility [Line Items]
Total unused lines of credit	$ 20,000