SECURITIES - Additional Information (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2014	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Proceeds from Sale of Available-for-sale Securities, Debt	$ 0	$ 10,416,000
Available-for-sale Securities, Gross Realized Gains		100,000
Available-for-sale Securities, Gross Realized Losses		$ 11,000
Federal Home Loan Bank Stock and Federal Reserve Bank Stock	31,800,000
Cost Method Investments, Fair Value Disclosure	31,800,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	774,123,000			$ 862,873,000
Accumulated unrealized losses	15,096,000			18,443,000
Securities Available For Sale Transferred To Held-To-Maturity	60,900,000		$ 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	1,700,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	499,646,000			664,476,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 9,255,000			$ 13,451,000
Common Stock, Shares, Outstanding	40,715,938			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	211,330
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	$ 1,700,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	21,500,000			$ 22,800,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	300,000			$ 400,000
Carrying Amount [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities pledged as collateral	187,600,000
Carrying Amount [Member] | Repurchase Agreement [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities pledged as collateral	183,100,000
Mortgage Backed Securities And Collateralized Mortgage Obligations Of Us Government Sponsored Entities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	609,600,000
Accumulated unrealized losses	12,000,000
Collateralized Loan Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	18,200,000
Private Collateralized Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	72,300,000
Accumulated unrealized losses	$ 1,400,000