Loans and Loans Held for Sale - Restructured Loans for Periods Presented (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended
	Mar. 31, 2014		Mar. 31, 2013	Mar. 31, 2014 Accruing TDRs [Member]	Dec. 31, 2013 Accruing TDRs [Member]	Mar. 31, 2014 Accruing TDRs [Member] Commercial Real Estate [Member]	Dec. 31, 2013 Accruing TDRs [Member] Commercial Real Estate [Member]	Mar. 31, 2014 Accruing TDRs [Member] Commercial and Industrial [Member]	Dec. 31, 2013 Accruing TDRs [Member] Commercial and Industrial [Member]	Mar. 31, 2014 Accruing TDRs [Member] Commercial Construction [Member]	Dec. 31, 2013 Accruing TDRs [Member] Commercial Construction [Member]	Mar. 31, 2014 Accruing TDRs [Member] Residential Mortgage [Member]	Dec. 31, 2013 Accruing TDRs [Member] Residential Mortgage [Member]	Mar. 31, 2014 Accruing TDRs [Member] Home Equity [Member]	Dec. 31, 2013 Accruing TDRs [Member] Home Equity [Member]	Mar. 31, 2014 Accruing TDRs [Member] Installment and Other Consumer [Member]	Dec. 31, 2013 Accruing TDRs [Member] Installment and Other Consumer [Member]	Mar. 31, 2014 Nonaccruing TDRs [Member]	Dec. 31, 2013 Nonaccruing TDRs [Member]	Mar. 31, 2014 Nonaccruing TDRs [Member] Commercial Real Estate [Member]	Dec. 31, 2013 Nonaccruing TDRs [Member] Commercial Real Estate [Member]	Mar. 31, 2014 Nonaccruing TDRs [Member] Commercial and Industrial [Member]	Dec. 31, 2013 Nonaccruing TDRs [Member] Commercial and Industrial [Member]	Mar. 31, 2014 Nonaccruing TDRs [Member] Commercial Construction [Member]	Dec. 31, 2013 Nonaccruing TDRs [Member] Commercial Construction [Member]	Mar. 31, 2014 Nonaccruing TDRs [Member] Residential Mortgage [Member]	Dec. 31, 2013 Nonaccruing TDRs [Member] Residential Mortgage [Member]	Mar. 31, 2014 Nonaccruing TDRs [Member] Home Equity [Member]	Dec. 31, 2013 Nonaccruing TDRs [Member] Home Equity [Member]	Mar. 31, 2014 Nonaccruing TDRs [Member] Installment and Other Consumer [Member]	Dec. 31, 2013 Nonaccruing TDRs [Member] Installment and Other Consumer [Member]	Mar. 31, 2014 Total TDRs [Member]	Dec. 31, 2013 Total TDRs [Member]	Mar. 31, 2014 Total TDRs [Member] Commercial Real Estate [Member]	Dec. 31, 2013 Total TDRs [Member] Commercial Real Estate [Member]	Mar. 31, 2014 Total TDRs [Member] Commercial and Industrial [Member]	Dec. 31, 2013 Total TDRs [Member] Commercial and Industrial [Member]	Mar. 31, 2014 Total TDRs [Member] Commercial Construction [Member]	Dec. 31, 2013 Total TDRs [Member] Commercial Construction [Member]	Mar. 31, 2014 Total TDRs [Member] Residential Mortgage [Member]	Dec. 31, 2013 Total TDRs [Member] Residential Mortgage [Member]	Mar. 31, 2014 Total TDRs [Member] Home Equity [Member]	Dec. 31, 2013 Total TDRs [Member] Home Equity [Member]	Mar. 31, 2014 Total TDRs [Member] Installment and Other Consumer [Member]	Dec. 31, 2013 Total TDRs [Member] Installment and Other Consumer [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans	$ 1,791	[1]	$ 2,584	$ 36,059	$ 39,229	$ 15,538	$ 19,711	$ 7,453	$ 7,521	$ 6,352	$ 5,338	$ 2,692	$ 2,581	$ 3,878	$ 3,924	$ 146	$ 154	$ 9,269	$ 10,067	$ 3,529	$ 3,898	$ 2,138	$ 1,884	$ 1,969	$ 2,708	$ 1,394	$ 1,356	$ 237	$ 218	$ 2	$ 3	$ 45,328	$ 49,296	$ 19,067	$ 23,609	$ 9,591	$ 9,405	$ 8,321	$ 8,046	$ 4,086	$ 3,937	$ 4,115	$ 4,142	$ 148	$ 157

[1] Excludes loans that were fully paid off or fully charged-off by period end. The pre-modification balance represents the balance outstanding prior to modification. The post-modification balance represents the outstanding balance at period end.