Loans and Allowance for Loan Losses - Summary of Impaired Loans, by Class (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Financial Receivables Impaired Or Restructured [Line Items]
With allowance recorded, Specific Related Allowance	$ 1,268	$ 824
Recorded Investment	9,525
Specific Related Allowance	1,268
Commercial Real Estate [Member]
Financial Receivables Impaired Or Restructured [Line Items]
With no allowance recorded, Recorded Investment	36,987	40,472
With no allowance recorded, Unpaid Principal Balance	50,287	62,034
With no allowance recorded, Specific Related Allowance
With no allowance recorded, Average Recorded Investment	38,730	37,376
With allowance recorded, Recorded Investment	9,344	3,603
With allowance recorded, Unpaid Principal Balance	19,951	3,818
With allowance recorded, Specific Related Allowance	1,087	701
With allowance recorded, Average Recorded Investment	6,474	14,379
Recorded Investment	46,331	44,075
Unpaid Principal Balance	70,238	65,852
Specific Related Allowance	1,087	701
Average Recorded Investment	45,204	51,755
Commercial and Industrial [Member]
Financial Receivables Impaired Or Restructured [Line Items]
With no allowance recorded, Recorded Investment	4,972	7,301
With no allowance recorded, Unpaid Principal Balance	6,613	8,669
With no allowance recorded, Specific Related Allowance
With no allowance recorded, Average Recorded Investment	6,136	8,304
With allowance recorded, Recorded Investment	181	122
With allowance recorded, Unpaid Principal Balance	190	130
With allowance recorded, Specific Related Allowance	181	123
With allowance recorded, Average Recorded Investment	152	126
Recorded Investment	5,153	7,423
Unpaid Principal Balance	6,803	8,799
Specific Related Allowance	181	123
Average Recorded Investment	6,288	8,430
Commercial Leases [Member]
Financial Receivables Impaired Or Restructured [Line Items]
With no allowance recorded, Recorded Investment	744	734
With no allowance recorded, Unpaid Principal Balance	744	734
With no allowance recorded, Specific Related Allowance
With no allowance recorded, Average Recorded Investment	739	758
With allowance recorded, Recorded Investment
With allowance recorded, Unpaid Principal Balance
With allowance recorded, Specific Related Allowance
With allowance recorded, Average Recorded Investment
Recorded Investment	744	734
Unpaid Principal Balance	744	734
Average Recorded Investment	739	758
Total Commercial Loans and Leases [Member]
Financial Receivables Impaired Or Restructured [Line Items]
With no allowance recorded, Recorded Investment	42,703	48,507
With no allowance recorded, Unpaid Principal Balance	57,644	71,437
With no allowance recorded, Specific Related Allowance
With no allowance recorded, Average Recorded Investment	45,605	46,438
With allowance recorded, Recorded Investment	9,525	3,725
With allowance recorded, Unpaid Principal Balance	20,141	3,948
With allowance recorded, Specific Related Allowance	1,268	824
With allowance recorded, Average Recorded Investment	6,626	14,505
Recorded Investment	52,228	52,232
Unpaid Principal Balance	77,785	75,385
Specific Related Allowance	1,268	824
Average Recorded Investment	52,231	60,943
Direct Installment [Member]
Financial Receivables Impaired Or Restructured [Line Items]
With no allowance recorded, Recorded Investment	12,047	10,577
With no allowance recorded, Unpaid Principal Balance	12,150	10,830
With no allowance recorded, Specific Related Allowance
With no allowance recorded, Average Recorded Investment	11,312	10,557
Recorded Investment	12,047	10,577
Unpaid Principal Balance	12,150	10,830
Average Recorded Investment	11,312	10,557
Residential Mortgages [Member]
Financial Receivables Impaired Or Restructured [Line Items]
With no allowance recorded, Recorded Investment	13,961	14,012
With no allowance recorded, Unpaid Principal Balance	14,507	14,560
With no allowance recorded, Specific Related Allowance
With no allowance recorded, Average Recorded Investment	88,787	13,565
Recorded Investment	13,961	14,012
Unpaid Principal Balance	14,507	14,560
Average Recorded Investment	88,787	13,565
Indirect Installment [Member]
Financial Receivables Impaired Or Restructured [Line Items]
With no allowance recorded, Recorded Investment	1,399	1,202
With no allowance recorded, Unpaid Principal Balance	2,861	2,633
With no allowance recorded, Specific Related Allowance
With no allowance recorded, Average Recorded Investment	1,301	1,127
Recorded Investment	1,399	1,202
Unpaid Principal Balance	2,861	2,633
Average Recorded Investment	1,301	1,127
Consumer Lines of Credit [Member]
Financial Receivables Impaired Or Restructured [Line Items]
With no allowance recorded, Recorded Investment	922	597
With no allowance recorded, Unpaid Principal Balance	1,000	668
With no allowance recorded, Specific Related Allowance
With no allowance recorded, Average Recorded Investment	760	573
Recorded Investment	922	597
Unpaid Principal Balance	1,000	668
Average Recorded Investment	760	573
Other [Member]
Financial Receivables Impaired Or Restructured [Line Items]
With no allowance recorded, Recorded Investment
With no allowance recorded, Unpaid Principal Balance
With no allowance recorded, Specific Related Allowance
With no allowance recorded, Average Recorded Investment
Recorded Investment
Unpaid Principal Balance
Specific Related Allowance
Average Recorded Investment