Loans - Past Due, Non-Accrual and Current Non-Covered Loans by Loan Portfolio Class (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	$ 23,614	$ 27,113
60-89 Days Past Due Loans	8,949	10,313
Accruing Loans 90 Days Or More Past Due	3,369	9,491
Non-Accrual Loans	68,433	95,063
Total Past Due Loans	104,365	141,980
Current Non-PCI Loans	11,033,458	10,619,364
Total Non-PCI Loans	11,137,823	10,761,344
Commercial Real Estate Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	7,481	10,328
60-89 Days Past Due Loans	5,389	7,019
Accruing Loans 90 Days Or More Past Due	2,212	7,591
Non-Accrual Loans	39,041	52,050
Total Past Due Loans	54,123	76,988
Current Non-PCI Loans	5,050,048	4,851,809
Total Non-PCI Loans	5,104,171	4,928,797
Consumer Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	3,350	3,792
60-89 Days Past Due Loans	788	784
Accruing Loans 90 Days Or More Past Due	161	118
Non-Accrual Loans	2,106	2,035
Total Past Due Loans	6,405	6,729
Current Non-PCI Loans	1,668,283	1,520,443
Total Non-PCI Loans	1,674,688	1,527,172
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	4,918	6,398
60-89 Days Past Due Loans	783	571
Accruing Loans 90 Days Or More Past Due	450	233
Non-Accrual Loans	8,096	21,029
Total Past Due Loans	14,247	28,231
Current Non-PCI Loans	1,896,743	1,791,905
Total Non-PCI Loans	1,910,990	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	3,493	9,142
60-89 Days Past Due Loans	57	2,442
Accruing Loans 90 Days Or More Past Due	2,212	7,591
Non-Accrual Loans	32,507	43,934
Total Past Due Loans	38,269	63,109
Current Non-PCI Loans	4,668,940	4,458,811
Total Non-PCI Loans	4,707,209	4,521,920
Construction [Member] | Commercial Real Estate Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	3,988	1,186
60-89 Days Past Due Loans	5,332	4,577
Accruing Loans 90 Days Or More Past Due	0	0
Non-Accrual Loans	6,534	8,116
Total Past Due Loans	15,854	13,879
Current Non-PCI Loans	381,108	392,998
Total Non-PCI Loans	396,962	406,877
Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	7,865	6,595
60-89 Days Past Due Loans	1,989	1,939
Accruing Loans 90 Days Or More Past Due	546	1,549
Non-Accrual Loans	19,190	19,949
Total Past Due Loans	29,590	30,032
Current Non-PCI Loans	2,418,384	2,455,207
Total Non-PCI Loans	2,447,974	2,485,239
Home Equity [Member] | Consumer Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	727	495
60-89 Days Past Due Loans	327	241
Accruing Loans 90 Days Or More Past Due	0	0
Non-Accrual Loans	1,985	1,866
Total Past Due Loans	3,039	2,602
Current Non-PCI Loans	397,264	408,273
Total Non-PCI Loans	400,303	410,875
Automobile [Member] | Consumer Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	2,190	2,957
60-89 Days Past Due Loans	320	489
Accruing Loans 90 Days Or More Past Due	144	85
Non-Accrual Loans	121	169
Total Past Due Loans	2,775	3,700
Current Non-PCI Loans	1,019,007	897,699
Total Non-PCI Loans	1,021,782	901,399
Other Consumer [Member] | Consumer Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	433	340
60-89 Days Past Due Loans	141	54
Accruing Loans 90 Days Or More Past Due	17	33
Non-Accrual Loans	0	0
Total Past Due Loans	591	427
Current Non-PCI Loans	252,012	214,471
Total Non-PCI Loans	$ 252,603	$ 214,898