Loans - Past Due, Non-Accrual and Current Non-Covered Loans by Loan Portfolio Class (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	$ 27,113	$ 36,021
60-89 Days Past Due Loans	10,313	13,665
Accruing Loans 90 Days Or More Past Due	9,491	8,665
Non-Accrual Loans	95,063	131,808
Total Past Due Loans	141,980	190,159
Current Non-PCI Loans	10,619,364	9,664,976
Total Non-PCI Loans	10,761,344	9,855,135
Commercial real estate loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	10,328	13,007
60-89 Days Past Due Loans	7,019	6,923
Accruing Loans 90 Days Or More Past Due	7,591	5,525
Non-Accrual Loans	52,050	73,430
Total Past Due Loans	76,988	98,885
Current Non-PCI Loans	4,851,809	4,073,054
Total Non-PCI Loans	4,928,797	4,171,939
Consumer loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	3,792	5,887
60-89 Days Past Due Loans	784	1,340
Accruing Loans 90 Days Or More Past Due	118	501
Non-Accrual Loans	2,035	3,331
Total Past Due Loans	6,729	11,059
Current Non-PCI Loans	1,520,443	1,393,767
Total Non-PCI Loans	1,527,172	1,404,826
Commercial and industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	6,398	3,397
60-89 Days Past Due Loans	571	181
Accruing Loans 90 Days Or More Past Due	233	283
Non-Accrual Loans	21,029	22,424
Total Past Due Loans	28,231	26,285
Current Non-PCI Loans	1,791,905	1,806,458
Total Non-PCI Loans	1,820,136	1,832,743
Commercial real estate [Member] | Commercial real estate loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	9,142	11,214
60-89 Days Past Due Loans	2,442	2,031
Accruing Loans 90 Days Or More Past Due	7,591	2,950
Non-Accrual Loans	43,934	58,625
Total Past Due Loans	63,109	74,820
Current Non-PCI Loans	4,458,811	3,697,264
Total Non-PCI Loans	4,521,920	3,772,084
Construction [Member] | Commercial real estate loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	1,186	1,793
60-89 Days Past Due Loans	4,577	4,892
Accruing Loans 90 Days Or More Past Due		2,575
Non-Accrual Loans	8,116	14,805
Total Past Due Loans	13,879	24,065
Current Non-PCI Loans	392,998	375,790
Total Non-PCI Loans	406,877	399,855
Residential mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	6,595	13,730
60-89 Days Past Due Loans	1,939	5,221
Accruing Loans 90 Days Or More Past Due	1,549	2,356
Non-Accrual Loans	19,949	32,623
Total Past Due Loans	30,032	53,930
Current Non-PCI Loans	2,455,207	2,391,697
Total Non-PCI Loans	2,485,239	2,445,627
Home equity [Member] | Consumer loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	495	391
60-89 Days Past Due Loans	241	311
Accruing Loans 90 Days Or More Past Due
Non-Accrual Loans	1,866	2,398
Total Past Due Loans	2,602	3,100
Current Non-PCI Loans	408,273	435,781
Total Non-PCI Loans	410,875	438,881
Automobile [Member] | Consumer loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	2,957	4,519
60-89 Days Past Due Loans	489	924
Accruing Loans 90 Days Or More Past Due	85	469
Non-Accrual Loans	169	305
Total Past Due Loans	3,700	6,217
Current Non-PCI Loans	897,699	780,311
Total Non-PCI Loans	901,399	786,528
Other Consumer [Member] | Consumer loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due Loans	340	977
60-89 Days Past Due Loans	54	105
Accruing Loans 90 Days Or More Past Due	33	32
Non-Accrual Loans		628
Total Past Due Loans	427	1,742
Current Non-PCI Loans	214,471	177,675
Total Non-PCI Loans	$ 214,898	$ 179,417