SECURITIES - Additional Information (Details) - USD ($)	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2014	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Proceeds from Sale of Available-for-sale Securities, Debt				$ 3,820,000	$ 12,211,000
Available-for-sale Securities, Gross Realized Gains	$ 1,700,000		$ 47,000	21,000	147,000
Available-for-sale Securities, Gross Realized Losses	0		$ 0	0	$ 11,000
Federal Home Loan Bank Stock and Federal Reserve Bank Stock	36,400,000			36,400,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	612,363,000			612,363,000			$ 862,873,000
Accumulated unrealized losses	10,545,000			10,545,000			18,443,000
Securities Available For Sale Transferred To Held-To-Maturity				66,900,000		$ 158,800,000
Available For Sale Securities Transferred To Held To Maturity Securities Unrealized Gain Loss				3,100,000		$ 3,100,000
Trading Securities, Unrealized Holding Loss				1,600,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	345,605,000			345,605,000			664,476,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	5,092,000			5,092,000			13,451,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	266,758,000			266,758,000			198,397,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 5,453,000			$ 5,453,000			$ 4,992,000
Common Stock, Shares, Outstanding	43,458,973			43,458,973			38,021,835
Stock Issued During Period, Value, Conversion of Convertible Securities, Net of Adjustments, Total		$ 6,200,000
Common Class B [Member]
Schedule of Available-for-sale Securities [Line Items]
Common Stock, Shares, Outstanding	11,330	211,330		11,330
Stock Issued During Period, Shares, Conversion of Convertible Securities		200,000
Common Class A [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Instrument, Convertible, Conversion Price		$ 1.6483
Stock Issued During Period, Shares, Conversion of Convertible Securities		348,335
Available-for-sale Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 1,600,000			$ 1,600,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	7,400,000			7,400,000			$ 22,800,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	100,000			100,000			400,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	7,400,000			7,400,000			$ 0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	100,000			100,000
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	0			0
Carrying Amount [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities pledged as collateral	183,300,000			183,300,000
Carrying Amount [Member] | Repurchase Agreement [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities pledged as collateral	167,600,000			167,600,000
Private Collateralized Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	512,400,000			512,400,000
Accumulated unrealized losses	9,100,000			9,100,000
Seasoned Residential Collateral Of Us Government Sponsored Entities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	33,000,000			33,000,000
Accumulated unrealized losses	$ 600,000			$ 600,000