STOCK-BASED COMPENSATION - Market Condition Restricted Shares, Stock Price Vesting (Details) - Market Condition Restricted Shares - Stock Price Vesting - Restricted Shares		1 Months Ended	3 Months Ended			6 Months Ended		12 Months Ended		24 Months Ended
	Feb. 26, 2016 item $ / shares shares	Jul. 31, 2017 $ / shares shares	Jun. 30, 2015 item $ / shares shares	Mar. 31, 2015 shares	Dec. 31, 2014 shares	Jun. 30, 2017 USD ($) item $ / shares shares	Mar. 31, 2015 item $ / shares	Dec. 31, 2012 shares	Dec. 31, 2011 shares	Dec. 31, 2012 item $ / shares
Stock-based compensation
Vesting period of performance shares after change of control	24 months
Shares
Outstanding (in shares)		69,500				69,500
Granted (in shares)
Outstanding (in shares)						69,500
Weighted Average Fair Value
Outstanding (in dollars per share) | $ / shares		$ 27.03				$ 27.03
Granted (in dollars per share | $ / shares
Outstanding (in dollars per share) | $ / shares						$ 27.03
Unrecognized compensation cost | $						$ 0
Mr. Albright
Stock-based compensation
Number of increments to vest | item	4		4
Restricted share award period after termination of employment	60 days		60 days
Period for average closing price	30 days		30 days
Restricted share award closing prices range per share, Minimum | $ / shares	$ 60		$ 60
Restricted share award closing prices range per share, Maximum | $ / shares	$ 75		$ 75
Number of increments vested | item						0
Stock based compensation, shares, surrendered	72,000
Stock based compensation, shares, permanently surrendered	68,000
Shares
Granted (in shares)	4,000		94,000						96,000
Expired (in shares)		32,000
Outstanding (in shares)	26,000
Mr. Patten
Shares
Granted (in shares)								17,000
Mr. Albright and Mr. Patten
Stock-based compensation
Number of increments to vest | item										6
Restricted share award period after termination of employment										60 days
Period for average closing price										60 days
Restricted share award closing prices range per share, Minimum | $ / shares										$ 36
Restricted share award closing prices range per share, Maximum | $ / shares										$ 65
Period subject to stock price condition										6 years
Number of increments vested | item						4
Mr. Smith
Shares
Granted (in shares)					2,500
Officer
Shares
Granted (in shares)				3,000
Mr. Smith and other Officer
Stock-based compensation
Number of increments to vest | item							2
Restricted share award period after termination of employment							60 days
Period for average closing price							60 days
Restricted share award closing prices range per share, Minimum | $ / shares							$ 60
Restricted share award closing prices range per share, Maximum | $ / shares							$ 65
Period subject to stock price condition							6 years
Number of increments vested | item						0