FAIR VALUE DISCLOSURES - Estimated Fair Values of Financial Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Financial assets
Investment securities held-to-maturity	$ 917,758	$ 2,664
Other investments	71,492	71,492
Loans, excluding covered loans	2,914,113	2,915,871
Covered loans	940,463	1,010,409
FDIC indemnification asset	156,397	173,009
Deposits
Noninterest-bearing	1,007,049	946,180
Savings	1,613,244	1,724,659
Time	1,491,132	1,654,662
Total deposits	5,400,915	5,642,840
Short-term borrowings	78,619	99,431
Carrying value
Financial assets
Cash and short-term investments	150,050	525,051
Investment securities held-to-maturity	917,758	2,664
Other investments	71,492	71,492
Loans Held-for-sale, Fair Value Disclosure	21,052	24,834
Loans, excluding covered loans	2,914,113	2,915,871
Covered loans	940,463	1,010,409
FDIC indemnification asset	156,397	173,009
Deposits
Noninterest-bearing	1,007,049	946,180
Interest-bearing demand	1,289,490	1,317,339
Savings	1,613,244	1,724,659
Time	1,491,132	1,654,662
Total deposits	5,400,915	5,642,840
Short-term borrowings	78,619	99,431
Long-term debt	75,745	76,544
Fair value
Financial assets
Cash and short-term investments	150,050	525,051
Investment securities held-to-maturity	916,727	2,893
Other investments	71,492	71,492
Loans Held-for-sale, Fair Value Disclosure	21,052	24,834
Loans, excluding covered loans	2,905,664	2,910,825
Covered loans	944,687	1,042,752
FDIC indemnification asset	135,655	151,114
Deposits
Noninterest-bearing	1,007,049	946,180
Interest-bearing demand	1,289,490	1,317,339
Savings	1,613,244	1,724,659
Time	1,500,832	1,664,457
Total deposits	5,410,615	5,652,635
Short-term borrowings	78,619	99,431
Long-term debt	80,155	81,168
Fair Value Measurements Using Level 1 | Fair value
Financial assets
Cash and short-term investments	150,050	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	78,619	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	916,727	2,893
Other investments	71,492	71,492
Loans Held-for-sale, Fair Value Disclosure	21,052	24,834
Loans, excluding covered loans	0	0
Covered loans	0	0
FDIC indemnification asset	0	0
Deposits
Noninterest-bearing	1,007,049	946,180
Interest-bearing demand	1,289,490	1,317,339
Savings	1,613,244	1,724,659
Time	1,500,832	1,664,457
Total deposits	5,410,615	5,652,635
Short-term borrowings	0	0
Long-term debt	80,155	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	2,905,664	2,910,825
Covered loans	944,687	1,042,752
FDIC indemnification asset	135,655	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