SHARE-BASED COMPENSATION, Summary of Stock Option Activity (Details) - $ / shares	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2016
Number of Shares Under Option
Outstanding at December 31, 2015	2,405,371
Options granted	426,390
Options exercised	(351,574)
Options forfeited	0
Outstanding at March 31, 2016	2,480,187
Options exercisable at March 31, 2016		1,376,812
Weighted- Average Exercise Price per Share
Outstanding at December 31, 2015	$ 21.39
Options granted	13.10
Options exercised	20.95
Options forfeited	0.00
Outstanding at March 31, 2016	$ 21.39	$ 23.50
Options exercisable at March 31, 2016		$ 16.35