Loans Receivable - Schedule of Aging of Non-Covered Loans (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Non-Covered Loans Excluding Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, 30-59 days	$ 7,710	$ 13,426
Past Due, 60-89 days	3,473	7,965
Past Due, Greater than 90 days	33,253	44,762
Total past due	44,436	66,153
Current	8,408,486	8,222,168
Total Non-covered loans, Net of Unearned Income	8,452,922	8,288,321
Recorded investment > 90 days and Accruing	269	1,075
Non-Covered Loans Excluding Acquired Loans [Member] | Commercial Loans [Member] | Commercial Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, 30-59 days	174
Past Due, 60-89 days
Past Due, Greater than 90 days	1,587	1,803
Total past due	1,761	1,803
Current	495,399	381,292
Total Non-covered loans, Net of Unearned Income	497,160	383,095
Recorded investment > 90 days and Accruing
Non-Covered Loans Excluding Acquired Loans [Member] | Commercial Loans [Member] | Commercial Real Estate - Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, 30-59 days	1,304	6,098
Past Due, 60-89 days	489	5,630
Past Due, Greater than 90 days	6,854	7,650
Total past due	8,647	19,378
Current	2,745,164	2,732,431
Total Non-covered loans, Net of Unearned Income	2,753,811	2,751,809
Recorded investment > 90 days and Accruing		2
Non-Covered Loans Excluding Acquired Loans [Member] | Commercial Loans [Member] | Commercial Business [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, 30-59 days	589	2,117
Past Due, 60-89 days	1,499	423
Past Due, Greater than 90 days	4,348	15,020
Total past due	6,436	17,560
Current	2,884,368	2,888,491
Total Non-covered loans, Net of Unearned Income	2,890,804	2,906,051
Recorded investment > 90 days and Accruing	143
Non-Covered Loans Excluding Acquired Loans [Member] | Residential Mortgage Loans [Member] | Residential Prime [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, 30-59 days	1,584	1,104
Past Due, 60-89 days	867	852
Past Due, Greater than 90 days	8,444	9,684
Total past due	10,895	11,640
Current	300,076	286,167
Total Non-covered loans, Net of Unearned Income	310,971	297,807
Recorded investment > 90 days and Accruing	126	1,073
Non-Covered Loans Excluding Acquired Loans [Member] | Residential Mortgage Loans [Member] | Residential Subprime [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, 30-59 days
Past Due, 60-89 days
Past Due, Greater than 90 days	2,438	1,626
Total past due	2,438	1,626
Current	115,167	114,939
Total Non-covered loans, Net of Unearned Income	117,605	116,565
Recorded investment > 90 days and Accruing
Non-Covered Loans Excluding Acquired Loans [Member] | Consumer and Other Loans [Member] | Home Equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, 30-59 days	1,940	1,956
Past Due, 60-89 days	264	569
Past Due, Greater than 90 days	7,458	6,808
Total past due	9,662	9,333
Current	1,112,644	1,091,894
Total Non-covered loans, Net of Unearned Income	1,122,306	1,101,227
Recorded investment > 90 days and Accruing
Non-Covered Loans Excluding Acquired Loans [Member] | Consumer and Other Loans [Member] | Indirect Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, 30-59 days	983	1,427
Past Due, 60-89 days	35	293
Past Due, Greater than 90 days	1,330	1,275
Total past due	2,348	2,995
Current	375,912	370,388
Total Non-covered loans, Net of Unearned Income	378,260	373,383
Recorded investment > 90 days and Accruing
Non-Covered Loans Excluding Acquired Loans [Member] | Consumer and Other Loans [Member] | Credit Card [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, 30-59 days	321	266
Past Due, 60-89 days	163	92
Past Due, Greater than 90 days	326	411
Total past due	810	769
Current	62,563	62,873
Total Non-covered loans, Net of Unearned Income	63,373	63,642
Recorded investment > 90 days and Accruing
Non-Covered Loans Excluding Acquired Loans [Member] | Consumer and Other Loans [Member] | Consumer - Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, 30-59 days	815	458
Past Due, 60-89 days	156	106
Past Due, Greater than 90 days	468	485
Total past due	1,439	1,049
Current	317,193	293,693
Total Non-covered loans, Net of Unearned Income	318,632	294,742
Recorded investment > 90 days and Accruing
Non-Covered Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, 30-59 days	4,021	3,251
Past Due, 60-89 days	1,216	2,580
Past Due, Greater than 90 days	34,596	37,265
Total past due	39,833	43,096
Current	547,226	506,422
Discount	(62,982)	(65,613)
Total Non-covered loans, Net of Unearned Income	524,077	483,905
Recorded investment > 90 days and Accruing	34,596	37,265
Non-Covered Acquired Loans [Member] | Commercial Loans [Member] | Commercial Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, 30-59 days	589	388
Past Due, 60-89 days	183
Past Due, Greater than 90 days	2,031	2,542
Total past due	2,803	2,930
Current	21,491	19,833
Discount	(3,088)	(2,532)
Total Non-covered loans, Net of Unearned Income	21,206	20,231
Recorded investment > 90 days and Accruing	2,031	2,542
Non-Covered Acquired Loans [Member] | Commercial Loans [Member] | Commercial Real Estate - Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, 30-59 days	1,103	1,798
Past Due, 60-89 days	642	1,963
Past Due, Greater than 90 days	25,471	27,967
Total past due	27,216	31,728
Current	356,025	345,286
Discount	(48,069)	(52,176)
Total Non-covered loans, Net of Unearned Income	335,172	324,838
Recorded investment > 90 days and Accruing	25,471	27,967
Non-Covered Acquired Loans [Member] | Commercial Loans [Member] | Commercial Business [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, 30-59 days	819	544
Past Due, 60-89 days	193
Past Due, Greater than 90 days	1,611	1,218
Total past due	2,623	1,762
Current	59,430	54,189
Discount	(4,769)	(2,914)
Total Non-covered loans, Net of Unearned Income	57,284	53,037
Recorded investment > 90 days and Accruing	1,611	1,218
Non-Covered Acquired Loans [Member] | Residential Mortgage Loans [Member] | Residential Prime [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, 30-59 days	332
Past Due, 60-89 days	93
Past Due, Greater than 90 days	363	226
Total past due	788	226
Current	21,510	18,796
Discount	7	(887)
Total Non-covered loans, Net of Unearned Income	22,305	18,135
Recorded investment > 90 days and Accruing	363	226
Non-Covered Acquired Loans [Member] | Consumer and Other Loans [Member] | Home Equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, 30-59 days	925	313
Past Due, 60-89 days	53	516
Past Due, Greater than 90 days	4,544	4,242
Total past due	5,522	5,071
Current	73,324	53,995
Discount	(5,966)	(5,623)
Total Non-covered loans, Net of Unearned Income	72,880	53,443
Recorded investment > 90 days and Accruing	4,544	4,242
Non-Covered Acquired Loans [Member] | Consumer and Other Loans [Member] | Indirect Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, 30-59 days	16	33
Past Due, Greater than 90 days	81	95
Total past due	97	128
Current	1,204	1,725
Discount	(16)
Total Non-covered loans, Net of Unearned Income	1,285	1,853
Recorded investment > 90 days and Accruing	81	95
Non-Covered Acquired Loans [Member] | Consumer and Other Loans [Member] | Consumer - Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, 30-59 days	237	175
Past Due, 60-89 days	52	101
Past Due, Greater than 90 days	495	975
Total past due	784	1,251
Current	14,242	12,598
Discount	(1,081)	(1,481)
Total Non-covered loans, Net of Unearned Income	13,945	12,368
Recorded investment > 90 days and Accruing	$ 495	$ 975