Loans - Recorded Investment in Loan Classes Based on Payment Activity (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Non-PCI Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	$ 4,045,138	$ 4,012,411
Non-PCI Loans [Member] | Residential Mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	2,457,677	2,485,239
Non-PCI Loans [Member] | Home Equity [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	402,793	410,875
Non-PCI Loans [Member] | Automobile Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	957,036	901,399
Non-PCI Loans [Member] | Other Consumer [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	227,632	214,898
PCI Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	742,599	806,268
PCI Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	186,000	201,197
PCI Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	474,646	521,249
PCI Loans [Member] | Construction [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	22,170	22,354
PCI Loans [Member] | Residential Mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	21,439	22,349
PCI Loans [Member] | Consumer [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	38,344	39,119
Performing Loans [Member] | Non-PCI Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	4,022,269	3,990,427
Performing Loans [Member] | Non-PCI Loans [Member] | Residential Mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	2,436,957	2,465,290
Performing Loans [Member] | Non-PCI Loans [Member] | Home Equity [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	400,783	409,009
Performing Loans [Member] | Non-PCI Loans [Member] | Automobile Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	956,897	901,230
Performing Loans [Member] | Non-PCI Loans [Member] | Other Consumer [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	227,632	214,898
Performing Loans [Member] | PCI Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	712,823	759,521
Performing Loans [Member] | PCI Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	171,482	185,185
Performing Loans [Member] | PCI Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	460,696	498,184
Performing Loans [Member] | PCI Loans [Member] | Construction [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	22,170	16,791
Performing Loans [Member] | PCI Loans [Member] | Residential Mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	20,878	21,381
Performing Loans [Member] | PCI Loans [Member] | Consumer [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	37,597	37,980
Non-Performing Loans [Member] | Non-PCI Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	22,869	21,984
Non-Performing Loans [Member] | Non-PCI Loans [Member] | Residential Mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	20,720	19,949
Non-Performing Loans [Member] | Non-PCI Loans [Member] | Home Equity [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	2,010	1,866
Non-Performing Loans [Member] | Non-PCI Loans [Member] | Automobile Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	139	169
Non-Performing Loans [Member] | Non-PCI Loans [Member] | Other Consumer [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans		0
Non-Performing Loans [Member] | PCI Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	29,776	46,747
Non-Performing Loans [Member] | PCI Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	14,518	16,012
Non-Performing Loans [Member] | PCI Loans [Member] | Commercial Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	13,950	23,065
Non-Performing Loans [Member] | PCI Loans [Member] | Construction [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	0	5,563
Non-Performing Loans [Member] | PCI Loans [Member] | Residential Mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	561	968
Non-Performing Loans [Member] | PCI Loans [Member] | Consumer [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	$ 747	$ 1,139