Borrowings - Summary of Information Pertaining to Borrowings (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Long Term And Short Term Debt [Line Items]
Short-term borrowings	$ 210,269	$ 173,847
Long-term borrowings	66,255	67,429
Total Borrowings	276,524	241,276
Short-term borrowings, Weighted Average Rate	0.25%	0.24%
Long-term borrowings, Weighted Average Rate	2.78%	2.80%
Total Borrowings, Weighted Average Rate	0.85%	0.96%
Securities Sold under Repurchase Agreements [Member]
Long Term And Short Term Debt [Line Items]
Short-term borrowings	25,269	33,847
Short-term borrowings, Weighted Average Rate	0.01%	0.01%
Short-Term Borrowings [Member]
Long Term And Short Term Debt [Line Items]
Short-term borrowings	185,000	140,000
Short-term borrowings, Weighted Average Rate	0.28%	0.30%
Other Long-Term Borrowings [Member]
Long Term And Short Term Debt [Line Items]
Long-term borrowings	20,636	21,810
Long-term borrowings, Weighted Average Rate	2.98%	3.01%
Junior Subordinated Debt Securities [Member]
Long Term And Short Term Debt [Line Items]
Long-term borrowings	$ 45,619	$ 45,619
Long-term borrowings, Weighted Average Rate	2.69%	2.70%