RELATED-PARTY TRANSACTIONS - Transactions with TWC Shared Opportunity Fund V, L.P., a Greater than 5 percent Shareholder (Details)							1 Months Ended
	Aug. 03, 2015 $ / shares shares	Mar. 16, 2015 shares	Jan. 20, 2015 shares	Jan. 05, 2015 shares	Jun. 03, 2013 shares	Nov. 01, 2010 $ / shares shares	Nov. 30, 2010 shares	Sep. 30, 2016 $ / shares	Dec. 31, 2015 shares	Dec. 31, 2014 shares	Dec. 10, 2014	May 29, 2013
Related Party Transaction [Line Items]
Exercise price of warrants for non-voting common stock (in dollars per share) | $ / shares						$ 11		$ 8.80
Tcw Shared Opportunity Fund
Related Party Transaction [Line Items]
Warrant exercisable period						5 years	5 years
Warrants issued (in shares)						240,000	240,000			240,000
Conversion ratio											1
Exercise price of warrants for non-voting common stock (in dollars per share) | $ / shares	$ 9.13					$ 11.00
Ownership percentage									3.50%
Tcw Shared Opportunity Fund | Voting Common Stock
Related Party Transaction [Line Items]
Maximum ownership percentage by noncontrolling owners to not be considered a bank holding company							4.99%
Maximum ownership percentage												9.99%
Shares outstanding										1,318,462
Shares exchanged		934	86,620	522,564	550,000
Common stock, shares outstanding (in shares)									1,318,462
Tcw Shared Opportunity Fund | Voting Common Stock | Common Stock
Related Party Transaction [Line Items]
Issuance of shares of voting common stock	70,690
Tcw Shared Opportunity Fund | Nonvoting Common Stock | Common Stock
Related Party Transaction [Line Items]
Issuance of shares of voting common stock	70,690