Loans - Past Due, Non-Accrual and Current Non-Covered Loans by Loan Portfolio Class (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	$ 36,397	$ 27,113
60-89 Days Past Due Loans	5,310	10,313
Accruing Loans 90 Days Or More Past Due	1,574	9,491
Non-Accrual Loans	64,640	95,063
Total Past Due Loans	107,921	141,980
Current Non-PCI Loans	10,844,074	10,619,364
Total Non-PCI Loans	10,951,995	10,761,344
Commercial Real Estate Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	21,785	10,328
60-89 Days Past Due Loans	2,377	7,019
Accruing Loans 90 Days Or More Past Due	137	7,591
Non-Accrual Loans	33,478	52,050
Total Past Due Loans	57,777	76,988
Current Non-PCI Loans	4,995,142	4,851,809
Total Non-PCI Loans	5,052,919	4,928,797
Consumer Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	2,685	3,792
60-89 Days Past Due Loans	613	784
Accruing Loans 90 Days Or More Past Due	205	118
Non-Accrual Loans	2,149	2,035
Total Past Due Loans	5,652	6,729
Current Non-PCI Loans	1,581,809	1,520,443
Total Non-PCI Loans	1,587,461	1,527,172
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	5,689	6,398
60-89 Days Past Due Loans	599	571
Accruing Loans 90 Days Or More Past Due	199	233
Non-Accrual Loans	8,293	21,029
Total Past Due Loans	14,780	28,231
Current Non-PCI Loans	1,839,158	1,791,905
Total Non-PCI Loans	1,853,938	1,820,136
Commercial Real Estate [Member] | Commercial Real Estate Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	16,169	9,142
60-89 Days Past Due Loans	2,377	2,442
Accruing Loans 90 Days Or More Past Due	137	7,591
Non-Accrual Loans	26,909	43,934
Total Past Due Loans	45,592	63,109
Current Non-PCI Loans	4,615,702	4,458,811
Total Non-PCI Loans	4,661,294	4,521,920
Construction [Member] | Commercial Real Estate Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	5,616	1,186
60-89 Days Past Due Loans	0	4,577
Accruing Loans 90 Days Or More Past Due	0	0
Non-Accrual Loans	6,569	8,116
Total Past Due Loans	12,185	13,879
Current Non-PCI Loans	379,440	392,998
Total Non-PCI Loans	391,625	406,877
Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	6,238	6,595
60-89 Days Past Due Loans	1,721	1,939
Accruing Loans 90 Days Or More Past Due	1,033	1,549
Non-Accrual Loans	20,720	19,949
Total Past Due Loans	29,712	30,032
Current Non-PCI Loans	2,427,965	2,455,207
Total Non-PCI Loans	2,457,677	2,485,239
Home Equity [Member] | Consumer Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	781	495
60-89 Days Past Due Loans	42	241
Accruing Loans 90 Days Or More Past Due	0	0
Non-Accrual Loans	2,010	1,866
Total Past Due Loans	2,833	2,602
Current Non-PCI Loans	399,960	408,273
Total Non-PCI Loans	402,793	410,875
Automobile [Member] | Consumer Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	1,841	2,957
60-89 Days Past Due Loans	524	489
Accruing Loans 90 Days Or More Past Due	199	85
Non-Accrual Loans	139	169
Total Past Due Loans	2,703	3,700
Current Non-PCI Loans	954,333	897,699
Total Non-PCI Loans	957,036	901,399
Other Consumer [Member] | Consumer Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	63	340
60-89 Days Past Due Loans	47	54
Accruing Loans 90 Days Or More Past Due	6	33
Non-Accrual Loans	0	0
Total Past Due Loans	116	427
Current Non-PCI Loans	227,516	214,471
Total Non-PCI Loans	$ 227,632	$ 214,898