LOANS RECEIVABLE AND THE ALLOWANCE FOR LOAN LOSSES (Fixed-rate and Adjustable-Rate Maturity) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Fixed-rate (term to maturity):
Maturing in one year or less	$ 145,752	$ 115,571
Maturing after one year through three years	193,168	184,707
Maturing after three years through five years	192,141	180,449
Maturing after five years through ten years	251,516	240,742
Maturing after ten years	611,185	572,793
Total fixed-rate loans	1,393,762	1,294,262
Adjustable-Rate (term to rate adjustment):
Maturing or repricing in one year or less	1,509,680	1,468,316
Maturing or repricing after one year through three years	527,346	416,433
Maturing or repricing after three years through five years	595,531	566,371
Maturing or repricing after five years through ten years	87,572	87,506
Maturing or repricing after ten years	927	932
Total adjustable-rate loans	2,721,056	2,539,558
Loans and Leases Receivable, Gross	4,114,818	3,833,820
Total loans outstanding	$ 4,114,818	$ 3,833,820	$ 3,522,912