CONDENSED FINANCIAL INFORMATION OF PARENT COMPANY (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Assets:
Cash and due from banks	$ 89,011	$ 92,342
Other assets	112,107	110,535
Total assets	5,463,658	5,528,237
Liabilities:
Subordinated debentures	108,250	129,271
Other liabilities	44,575	50,310
Total liabilities	4,874,537	4,982,034
Stockholders' equity	589,121	546,203	478,797	506,773
Total liabilities and stockholders' equity	5,463,658	5,528,237
Parent company
Assets:
Cash and due from banks	28,472	35,900
Investments in subsidiaries	649,656	625,494
Other assets	20,174	22,455
Total assets	698,302	683,849
Liabilities:
Subordinated debentures	108,250	129,271
Other liabilities	931	8,375
Total liabilities	109,181	137,646
Stockholders' equity	589,121	546,203
Total liabilities and stockholders' equity	$ 698,302	$ 683,849