CASH AND SECURITIES (Schedule of Investments) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Schedule of Investments [Line Items]
Interest-bearing deposits included in cash and due from banks	$ 54,995	$ 67,638
Marketable securities	582,537	635,265
Federal Home Loan Bank stock	27,036	35,390
Interest-bearing deposits and marketable securities	664,568	738,293
U.S. Government and agency obligations [Member]
Schedule of Investments [Line Items]
Marketable securities	33,421	61,327
Total municipal bonds [Member]
Schedule of Investments [Line Items]
Marketable securities	171,419	153,804
Taxable municipal bonds [Member]
Schedule of Investments [Line Items]
Marketable securities	29,566	34,216
Tax exempt municipal bonds [Member]
Schedule of Investments [Line Items]
Marketable securities	141,853	119,588
Corporate bonds [Member]
Schedule of Investments [Line Items]
Marketable securities	25,936	44,154
Total Mortgage-backed or related securities [Member]
Schedule of Investments [Line Items]
Marketable securities	326,307	350,721
1-4 residential agency guaranteed [Member]
Schedule of Investments [Line Items]
Marketable securities	58,825	58,117
1-4 residential other [Member]
Schedule of Investments [Line Items]
Marketable securities	713	1,051
Multifamily agency guaranteed [Member]
Schedule of Investments [Line Items]
Marketable securities	256,272	281,319
Multifamily other [Member]
Schedule of Investments [Line Items]
Marketable securities	10,497	10,234
Asset-backed securities [Member]
Schedule of Investments [Line Items]
Marketable securities	25,395	25,191
Student Loan Marketing Association SLMA [Member]
Schedule of Investments [Line Items]
Marketable securities	15,629	15,681
Other Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Marketable securities	9,766	9,510
Equity securities (excludes FHLB stock) [Member]
Schedule of Investments [Line Items]
Marketable securities	$ 59	$ 68