SHARE-BASED PAYMENT - Plan Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Restricted shares
Restricted Shares - Shares
Nonvested at beginning of period (in shares)	1,312,774
Granted (in shares)	645,533
Vested (in shares)	(452,856)
Forfeited (in shares)	(23,968)
Nonvested at end of period (in shares)	1,481,483	1,312,774
Restricted Shares - Weighted Average Grant-date Fair Value
Nonvested at beginning of period (in dollars per share)	$ 19.99
Granted (in dollars per share)	21.51	$ 21.03	$ 16.60
Vested (in dollars per share)	19.38
Forfeited (in dollars per share)	27.78
Nonvested at end of period (in dollars per share)	$ 20.71	$ 19.99
Additional disclosures
Fair value, vested shares (in dollars)	$ 10,300	$ 9,600	$ 6,200
Unrecognized compensation
Unrecognized compensation for outstanding restricted shares	$ 17,500
Unrecognized compensation cost, period for recognition	2 years 9 months 18 days
Stock options
Options
Outstanding at beginning of period (in shares)	1,106,352
Granted (in shares)	207,180
Exercised (in shares)	(18,157)
Outstanding at end of period (in shares)	1,295,375	1,106,352
Exercisable at end of period (in shares)	815,080
Weighted Average Exercise Price
Outstanding at beginning of period (in dollars per share)	$ 16.30
Granted (in dollars per share)	20.40
Exercised (in dollars per share)	26.97
Outstanding at end of period (in dollars per share)	16.97	$ 16.30
Exercisable at end of period (in dollars per share)	$ 16.14
Weighted-Average Remaining Contract Life (Years)
Outstanding at end of period (in years)	7 years
Exercisable at end of period (in years)	6 years 2 months 12 days
Aggregate Intrinsic Value
Outstanding at end of period (in dollars)	$ 18,436
Exercisable at end of period (in dollars)	12,279
Intrinsic value of options exercised, (in dollars)	200	$ 2,600	100
Cash received from the exercise of options	0	$ 0	$ 0
Unrecognized compensation
Unrecognized compensation cost for outstanding options	$ 1,700
Unrecognized compensation cost, period for recognition	1 year 8 months 12 days