SECURITIES - Amortized Cost and Fair Value of Securities by Contractual Maturity (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Amortized Cost
Due in less than one year	$ 100
Due after one year through five years	567
Due after five years through ten years	8,025
Due after ten years	29,926
Total	38,618
Amortized Cost	671,051	658,458
Fair Value
Due in less than one year	100
Due after one year through five years	580
Due after five years through ten years	7,936
Due after ten years	29,945
Total	38,561
Securities available for sale (at fair value)	658,512	641,611
Mortgage-Backed Securities of U.S. Government Sponsored Entities [Member]
Amortized Cost
Amortized Cost	153,330	129,468
Fair Value
Securities available for sale (at fair value)	151,310	126,735
Collateralized Mortgage Obligations of U.S. Government Sponsored Entities [Member]
Amortized Cost
Amortized Cost	369,042	383,392
Fair Value
Securities available for sale (at fair value)	358,113	369,421
Private Mortgage-Backed Securities [Member]
Amortized Cost
Amortized Cost	29,838	29,800
Fair Value
Securities available for sale (at fair value)	29,495	29,574
Private Collateralized Mortgage Obligations [Member]
Amortized Cost
Amortized Cost	80,223	76,520
Fair Value
Securities available for sale (at fair value)	81,033	76,838
No Contractual Maturity [Member]
Amortized Cost
Amortized Cost	0
Fair Value
Securities available for sale (at fair value)	$ 0