FAIR VALUE DISCLOSURES - Estimated Fair Values of Financial Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Financial assets
Investment securities held-to-maturity	$ 822,319	$ 2,664
Other investments	71,492	71,492
Loans, excluding covered loans	3,016,867	2,915,871
Covered loans	776,620	1,010,409
FDIC indemnification asset	130,476	173,009
Deposits
Noninterest-bearing	1,063,654	946,180
Savings	1,568,818	1,724,659
Time	1,199,296	1,654,662
Total deposits	4,944,611	5,642,840
Short-term borrowings	88,190	99,431
Carrying value
Financial assets
Cash and short-term investments	175,676	525,051
Investment securities held-to-maturity	822,319	2,664
Other investments	71,492	71,492
Loans Held-for-sale, Fair Value Disclosure	23,530	24,834
Loans, excluding covered loans	3,016,867	2,915,871
Covered loans	776,620	1,010,409
FDIC indemnification asset	130,476	173,009
Deposits
Noninterest-bearing	1,063,654	946,180
Interest-bearing demand	1,112,843	1,317,339
Savings	1,568,818	1,724,659
Time	1,199,296	1,654,662
Total deposits	4,944,611	5,642,840
Short-term borrowings	371,190	99,431
Long-term debt	75,521	76,544
Fair value
Financial assets
Cash and short-term investments	175,676	525,051
Investment securities held-to-maturity	830,540	2,893
Other investments	71,492	71,492
Loans Held-for-sale, Fair Value Disclosure	23,530	24,834
Loans, excluding covered loans	3,020,686	2,910,825
Covered loans	790,207	1,042,752
FDIC indemnification asset	116,051	151,114
Deposits
Noninterest-bearing	1,063,654	946,180
Interest-bearing demand	1,112,843	1,317,339
Savings	1,568,818	1,724,659
Time	1,206,006	1,664,457
Total deposits	4,951,321	5,652,635
Short-term borrowings	371,190	99,431
Long-term debt	79,921	81,168
Fair Value Measurements Using Level 1 | Fair value
Financial assets
Cash and short-term investments	175,676	525,051
Investment securities held-to-maturity	0	0
Other investments	0	0
Loans Held-for-sale, Fair Value Disclosure	0	0
Loans, excluding covered loans	0	0
Covered loans	0	0
FDIC indemnification asset	0	0
Deposits
Noninterest-bearing	0	0
Interest-bearing demand	0	0
Savings	0	0
Time	0	0
Total deposits	0	0
Short-term borrowings	371,190	99,431
Long-term debt	0	0
Fair Value Measurements Using Level 2 | Fair value
Financial assets
Cash and short-term investments	0	0
Investment securities held-to-maturity	830,540	2,893
Other investments	71,492	71,492
Loans Held-for-sale, Fair Value Disclosure	23,530	24,834
Loans, excluding covered loans	0	0
Covered loans	0	0
FDIC indemnification asset	0	0
Deposits
Noninterest-bearing	1,063,654	946,180
Interest-bearing demand	1,112,843	1,317,339
Savings	1,568,818	1,724,659
Time	1,206,006	1,664,457
Total deposits	4,951,321	5,652,635
Short-term borrowings	0	0
Long-term debt	79,921	81,168
Fair Value Measurements Using Level 3 | Fair value
Financial assets
Cash and short-term investments	0	0
Investment securities held-to-maturity	0	0
Other investments	0	0
Loans Held-for-sale, Fair Value Disclosure	0	0
Loans, excluding covered loans	3,020,686	2,910,825
Covered loans	790,207	1,042,752
FDIC indemnification asset	116,051	151,114
Deposits
Noninterest-bearing	0	0
Interest-bearing demand	0	0
Savings	0	0
Time	0	0
Total deposits	0	0
Short-term borrowings	0	0
Long-term debt	$ 0	$ 0