Loans - Recorded Investment in Loan Classes Based on Payment Activity (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 4,012,411	$ 3,850,453
Non-PCI Loans [Member] | Residential mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,485,239	2,445,627
Non-PCI Loans [Member] | Home equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	410,875	438,881
Non-PCI Loans [Member] | Automobile loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	901,399	786,528
Non-PCI Loans [Member] | Other Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	214,898	179,417
PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	806,268	1,167,664
PCI Loans [Member] | Commercial and industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	201,197	298,600
PCI Loans [Member] | Commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	521,249	765,893
PCI Loans [Member] | Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	22,354	27,513
PCI Loans [Member] | Residential mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	22,349	26,461
PCI Loans [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	39,119	49,197
Performing Loans [Member] | Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	3,990,427	3,814,499
Performing Loans [Member] | Non-PCI Loans [Member] | Residential mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,465,290	2,413,004
Performing Loans [Member] | Non-PCI Loans [Member] | Home equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	409,009	436,483
Performing Loans [Member] | Non-PCI Loans [Member] | Automobile loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	901,230	786,223
Performing Loans [Member] | Non-PCI Loans [Member] | Other Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	214,898	178,789
Performing Loans [Member] | PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	759,521	1,095,804
Performing Loans [Member] | PCI Loans [Member] | Commercial and industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	185,185	292,163
Performing Loans [Member] | PCI Loans [Member] | Commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	498,184	715,812
Performing Loans [Member] | PCI Loans [Member] | Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	16,791	17,967
Performing Loans [Member] | PCI Loans [Member] | Residential mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	21,381	22,173
Performing Loans [Member] | PCI Loans [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	37,980	47,689
Non-Performing Loans [Member] | Non-PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	21,984	35,954
Non-Performing Loans [Member] | Non-PCI Loans [Member] | Residential mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	19,949	32,623
Non-Performing Loans [Member] | Non-PCI Loans [Member] | Home equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,866	2,398
Non-Performing Loans [Member] | Non-PCI Loans [Member] | Automobile loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	169	305
Non-Performing Loans [Member] | Non-PCI Loans [Member] | Other Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans		628
Non-Performing Loans [Member] | PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	46,747	71,860
Non-Performing Loans [Member] | PCI Loans [Member] | Commercial and industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	16,012	6,437
Non-Performing Loans [Member] | PCI Loans [Member] | Commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	23,065	50,081
Non-Performing Loans [Member] | PCI Loans [Member] | Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	5,563	9,546
Non-Performing Loans [Member] | PCI Loans [Member] | Residential mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	968	4,288
Non-Performing Loans [Member] | PCI Loans [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 1,139	$ 1,508